On more than one occasion when I have copied data to a dual-layer DVD the data has gone missing from the DVD. That is, when I insert the DVD into the computer and read the DVD the data is not present. Would changing to a different brand of dual layer DVDs prevent the loss of this material? Also, are dual-layer DVDs as reliable as single layer DVDs? On a separate issue, I have successfully saved some YouTube videos on my computer using the Any Video Converter utility. The videos play perfectly fine on my computer in Windows Media Player, but when I attempt to play the same download on another computer only the audio is played. Why is this video restricted to only playing correctly on my home computer? The computer is running Windows XP.

The issue you are experiencing with data going missing from dual-layer DVDs sounds like a potential problem with the DVD burning/copying process. If you are inserting the DVD and an error message appears indicating that the DVD disc cannot be read, whereas on previous occasions it could be read without issue, then this indicates something is not right with the DVD itself. However, from your description it seems that you are inserting the DVD and the disc reads, but the data you require is not present. In this case, it seems like the data is not being written to the DVD correctly. Since you are using Windows XP there is no in-built DVD recording software within this version of Windows, so you must be using a third-party utility to create the DVDs (such as Nero or like). Make sure that you are correctly burning and finalising the DVD during the burning process. Once the burn has completed, immediately reinsert the DVD into the drive and verify that it is readable. However, you have likely already been doing this and the reason it could be working is because the files which should have been burned to the DVD maybe cached on your computer, giving the indication that they have been successfully burned to the DVD, whereas in fact they are actually still on your local hard drive, but just looking as if they have been burned to the DVD. This is a bit like the inbuilt Windows XP CD burning feature, where you drag and drop files directly onto the CD drive. Upon opening the CD drive the files appear as if they are on the CD, but in actual fact they are still on the local computer, but are appearing in the CD as “ready to copy” to the CD, and you still need to click the button to burn the files to the CD. Unfortunately, as I do not know the exact DVD writing software that you are using I cannot provide step-by-step advice on the process for correctly burning a DVD so you will need to investigate and check these steps yourself. However, to provide a more reliable test of the burned DVD I would suggest that after you have completed the DVD burning process you restart the computer and then check the DVD contents, as this may clear the cache of any files which have been staged for copying to the DVD, allowing you to only see the files which are on the DVD rather than files which are staged to be copied to the DVD. Even better, if you have a completely different computer which can be used to test the DVD then use that computer as a test-bench. If you need further assistance as the burning process is still not working correctly then please contact me again with details about the software that you are using and the exact process which you are following to burn the DVDs.

The second part of your question addresses the longevity of dual-layer DVDs compared with single-layer DVDs. This is an interesting question and one that does not yet have a definitive answer since dual-layer DVDs are more recent than single-layer DVDs and recordable CDs. In theory, dual-layer DVDs are quite structurally similar to single-layer DVDs with the obvious exception that there are two layers on the DVD with a gap between the two recording surfaces. The main factor which influences the longevity of the disc is the quality of the composition of the disc itself, together with the treatment and storage of the disc (in particular, avoiding exposing the disc to a large amount of light and humidity), as opposed to the number of layers. Many people feel that using dual-layer DVD is more of a risk not due to the uncertain nature of the technology, or because if the disc does fail (for whatever reason) you will lose more data simply because the disc can store more data. As a rule of thumb, if you are burning something “irreplaceable” to a DVD (or any type of removable media) for archival purposes then you should make multiple copies of that data across different media. In a perfect world, each copy should then be stored in a different location. The media will not last forever, so it greatly depends on the quality and treatment of the media. Therefore, it is always best to purchase well-known brand name media with a good track record, rather than a no-name brand with potentially questionable quality.

Your second question about saving videos from YouTube is related to the format in which the video has been saved. Every video is encoded in a particular format using something called a codec. The codec is a program that can encode and decode a data stream, which in this case is a video. The codec allows the video to be compressed into a reasonable size, so that it does not take up an inordinate amount of space. Furthermore, it also allows a video to be encoded in a common language so that the playing computer can determine the format of the video and then load an appropriate decoder so that the video can be played. However, not all computers have all the required decoders installed. In your situation, it seems that the computer which you are using to save the YouTube videos has the appropriate codec installed (which includes both the encoder and decoder). Most likely, this was installed by the Any Video Converter utility as it needs to encode the saved YouTube videos. By virtue of having this utility installed, your computer now has the required codec installed to playback the videos through Windows Media Player as well. However, other computers may not have the codec installed. In fact, it is highly unlikely that the codec would be installed on other computers unless the user specifically installed the codec, or installed another piece of software that requires and included the codec. In most cases, the audio stream is encoded using a relatively standard codec but the video stream encodes using a specific codec. This is why the audio is playing back correctly on the other computer, but you are not getting any video.

Reviewing the Any Video Converter website I cannot easily tell which codecs are being used. Therefore, your best option would be to download VLC Media Player on the other computer. VLC Media Player is a free, open-source media player which can practically play any video or audio file. It has a fairly exhaustive list of codecs in-built, so you should not need to download any additional codecs to playback the video file. You can downloaded VLC from www.videolan.org. Furthermore, VLC Media Player does not require installation to run. Therefore, if you would prefer not to install software on the other computer you could download and extract the VLC files onto a USB drive (or like) and run the program directly off the removable media, rather than installing the program on the other computer.

As a final note, while utilities are available to download videos off YouTube everyone should make sure that they observe any relevant copyright laws or legislation before saving or downloading videos from YouTube.