Each villain only gets a few seconds, or so it seems for most of them.  This makes them just seem like so kind of flashy side attraction we aren't supposed to care about.  Once Batman fell in the water I got confused as to what was happening all together.  I know it is tempting to put in as many villains as you can, but it usually doesn't work as each one doesn't get their due to to shine.  The inclusion of many characters works better when you just see glimpses of them, like a line of cells in Arkham or something like that.  Introducing them for a few seconds only to have them punched away is a let down. 

Also why do you put long credits in the middle of your video and then have a scene after it?  The only reason why I caught it in the Suicide Squad was because I saw someone credited that hadn't been in the video yet.  Not many people are willing to sit through a minute of credits on a Youtube video, so this scene will get missed most of the time.  I know it's fun and polite to credit your friends and all, so I wouldn't say don't do it, but don't have a post credit scene because most people will miss it.

I guess this is a bit of a nitpick, and I'm no expert on comic chemicals, but isn't the Scarecrow gas supposed to bring out the person's greatest fear?  I don't know why Batman would be afraid of himself, yet also be able to defeat most of them in one punch.  I feel you were trying to jam in a bunch of other characters here as well, but the same thing applies to the bat suits as the villains, don't bring them in if they aren't needed unless it is only for a quick visual cameo.

the Joker's face during TV appearance.  I though his face looked too big.

You not only wanted to show off your VFX and animations, you wanted to let us see how many minifigs you own. And that was the reason why we saw bat-men in Batman's fears (even though we are confused why he fears himself, we understand why you put them in.