Write playlist index number into the id3v2 "track" field (and playlist title into the "album" field)

[NelsonSR]

Many YouTube video playlist with screencasts (video tutorials) has a very specific order, if you watch them on the web page all of them will play in the intended order, but once all of them are downloaded locally you will notice that that order is gone, because the video titles (and the filename) has not index number correlative on it (no even in the id3v2 track field), so the order is now alphabetic.

There's two approaches to solve this issue:

1. Rename all the files putting the play-list index correlative in the filename.
2. Write the play-list correlative into the id3v2 track field (then sort them by the respective column in the video player).

The first approach could be ok, except if you want re-download the same file in order to get missing metadata. The second will avoid the prior issue, but no all the video player (specially in Android) has that feature), but it will be a piece of cake to rename them in batch using a tag editor (I use kid3 and sometimes EasyTag) having the track number.

So, my suggestion is: write the playlist index number in the id3v2 track field using the --add-metadata but only when the playlist variable is in the URL query string. Even better: in that case it would retrieve too the playlist title and write it into the id3v2 album field.