The support for playback of music/vids inside a tarball would be good to complete, as 1 000 000 files made into 1 file would be less on the drive and moving the whole library becomes faster when you only need to mirror the missing or corrupted files after unpacking the tar.
I've tested VLC v1.1.11 to read a tarball quite well (when it couldn't get much of one few versions back), but how good is the support, code-wise ?
Basically, by my testing, the total length of media inside the tar varies from the reality: it can be exact or 1 second longer/shorter or minutes longer/shorter, causing the playback to stop when skipping over to the end having nothing. That problem seems to be caused by lack of table-of-contents, as indicated by Wikipedia. Here, if VLC would read the file and make its own TOC consisting of starting & ending points of files, along with the tag data, the support is more complete if not complete altogether; don't know if it's possible to read the tag data without unpacking ...