Over-tagging?
It sounds like an idea sprung out from over-optimization, which can give a negative penalty on websites. Never heard of it on YouTube, or any other tagging platform for that matter. Now, obviously, you shouldn't repeat the same tags over and over again (aka: "golden bananas, golden banana, golds banana, banana golden, banana gold, gold, gold, gold, banana, banana, banana").
Making variations of the same tag, and making tags centred around the same keyword, is not the same thing as basically posting the same tag over and over again. Keep in mind that tags can be phrases, not just single words.
So, at least according to me, use as many tags as possible (or rather, use the full amount of allotted space you can, don't just focus on having >more< tags).
Out of curiosity, what did you put into ubersuggest? I've had pretty decent luck with it.
No, I just put terms that are not that popular. It's working now
So, I got this video: The Walking Dead Game Tribute Song | ORIGINAL TRIBUTE SONG | A Song About The Walking Dead..... The tags I put: the walking dead game, the walking dead theme song, let's play the walking dead, clementine and lee tribute, music for the walking dead, a song for the walking dead, a song about the walking dead, the walking dead game soundtrack, telltale games, tribute song, original tribute song, clementine, lee, tribute, the walking dead music video.... (and so forth) Are these good tags? It actually ranks me no.5 when I type: the walking dead tribute song