I got a d3100 over christmas and I really do love it. Like its a great camera all around, but for filming I would have to say t2i. biggest thing I didnt know about which I really should have looked into was the options for more frames per second. while the d3100 shines when its at full hd only at 24 fps, the t2i can get 60 fps at 720 which makes for some smooth slow motion and stuff. hope this helps. I have some clips from a d3100 if you want to look too