Similar lyrics

"Also performed by" is the least problematic way of attributing lyrics to another performer. When the very first performer is unknown (in case of folk songs, etc.) it is also the only possible way of arranging the lyrics' performers list.
As for the number of videos - it could be possibly increased for there's usually a lot of blank space to the right of a song text (when viewed on a PC, of course). The reason is that many artists have multiple variants of a same song's performance (different music, alternative lyrics). In case of minor text variations a combination of footnotes/alt.videos could possibly save some time for translators/viewers.
And for a case when two or more artists co-produced a song there could be a "featuring artist" field, I suppose.

This is on one level a good idea because it is very difficult to know if a song has been previously submitted by another artist in a variant or if that is the original or a cover. It is also very helpful to list adaptations of songs in other languages from the original. My experience is that to do that well takes a lot of specialized and time-consuming research to determine the original from the cover and the adaptation from the original. There is a site "secondhandsongs" that does a thorough job on this and it is heavily administrated, which is good, but even it is incomplete and I think it is a hopeless cause to try to regulate this. There is also "discogs" that is a great place to determine what was released and when, but again it is time-consuming to get to the bottom of things, and even then there are lapses that turn up when confronted with the vast number of singles and albums out there.

On another level and in the end, I think that you really shouldn't limit the submission of multiple versions or covers or adaptations. Artists usually vary the lyrics when they do a cover, and at times there are different adaptations into the same language. Why not offer all these versions for your audience? Plus, the rule has been that, if there is a video, there can be another submission, and I am not sure how you change that at this point without having a lot of users delete their accounts if you start deleting their contributions.

In addition, the current generosity to different artists and their covers/adaptations makes sense because, despite this site being about lyrics and translations, it is also about artists simply by how it is set up. When you start exploring an artist, you want to hear his or her covers and adaptations. Unless you change the ability of any user to add any video to any lyric, you will remove this feature of the site.

Summary: I am liking more cross-references but I am opposed to the idea of limiting submissions of covers or adaptations in any way. I think what we have now is pretty fantastic.

Алла Пугачёва спело множество песен, её песни перепеты многими исполнителями. И текст их вариантов песен, могут и должны быть на этом сайте.

Прошу прощения ( за мою демагогию), если я верно понял о чём речь идёт на форуме.