I have had several of my videos blocked as well, but I was not threatened with an account suspension. Instead, I had the option to change the audio and get the vids back up again. Nearly 40 of my mvs now have different songs in them.
What's causing a lot of the deletions now is a copyright claim wave by Warner Music Group. According to what I heard, there's some kind of dispute going on between YT and Warner, and until it is settled, more vids will be pulled.
Not only are fanmv makers effected, but from what I heard, even official bands and official videos are being taken down as well. Some bands whose music is being pulled from YT include Linkin Park, Within Temptation, Breaking Benjamin, and Three Days Grace.
LBTFan13, I remembered that some of your mvs had Linkin Park songs, am I right? That is why they were blocked. At least two of my mvs were blocked because I had LP songs in them, and such they were switched out using AudioSwap. Your remaining mv, the Littlefoot tribute, was spared because the song you used is listed in AudioSwap. The songs in AudioSwap are, currently, safe to use.
There seems to be a new policy regarding account deletions. Neravaira has had almost 60 of her videos taken down without losing her account, and was only threatened with an account suspension when one of her Bryan Adams vids was detected. According to her theory, YT will not delete accounts based on number of vids taken down, but instead by certain artists and bands that may be used. In this case, Bryan Adams's music will get you banned.