It looks like your budget is around $1000... I wonder if a better approach would be a GH3 + Metabones Nikon Speed Booster. That will have advantages over the 60D & 70D. That should run about $1000 and will have many advantages over APS-C Canons. I personally use a GH4 and A7S. Both have advantages over the canons, but are outside of your price range. Of the two, I like the GH4 more, however the A7S has its obvious advantages (FF sensor & high ISO performance). I used to own a pair of GH3s as well, and although the GH4 is a better camera, the GH3s are almost there.
I only have experience with a 5D mkII and 5D mkIII from Canon in terms of video so I cannot comment on the 60D/70D. Of the two, I would think the 70D has an advantage as I remember Canon put some thought into video when it was released. If your daughter is really comfortable using Canon, then go for it, but honestly other brands are better now.