I watched the first and only half of the second so far; I'll finish the second one soon.
I figure since I've watched quite a few fan-made "videos", often revolving around anime, I figure I'll try to be as critical and fair as I can so you can improve on any mistakes.
I like that you choose some instrumentals for the videos, although unless you made the song yourself with your own orchastra, I'm curious as to which songs on used. "The Return" I thought was done better, so far, than "Panic in the Sky". If I had one piece of advice to give, though, it is that fast-fowarding the animation to fit the video, outside of MTV and especially with your orchastra, non-rock style songs, looks a little awkward. You used that a lot in "Panic" and it felt weird. For some reason, slow-mo works better than fast-foward for this kind of thing. Don't ask why, because I can't give a good reason. True, I imagine it is hard to pace a video directly with the music without fast-fowarding, but that is why making videos is an art into itself. I've seen some brilliantly done fan-vidoes. I've also seen some average ones and some that were outright terrible. I can only imagine that with "Panic", you had not only a long song, but a LOT of footage; nearly the entire 22 minute episode was devoted to a battle, and you're trying to make it fit into a song that is under 7 minutes. Your ambitiousness to include it all was perhaps a double edged sword, as the FF stuff looked a little awkward. "Return" had a much shorter action sequence, which I believe you paced a little better because it was, well half as long. That's natural. Still, neither were bad, I just felt "Return" was better done, even if "Panic" and much of the action from Season 4 easily outshined it. I never realized how many "missed shots" the heroes in space had against AMAZO. And I only saw "Panic" once so I forgot some of the tiny bits, like Vigilante actually taking down Juice or The Ray actually coordinating 3 Juice's to get crushed under a falling Longshadow.
Both of these were fine. If you made vidoes of, say, "Divided We Fall", I'd be interested in your muscial choice.