Heya,
The 70D has no issues that should be a concern for you unless ETTL with a bounced flash is something you do a lot of. If you just want a good working camera that has video AF and all that jazz, a refurb/used 70D is the best bargain priced option for you. You can get this for around $600 sometimes. Just hunt around. If you're wanting video & AF, this is the cheapest dSLR approach that does it decently without moving to another system if you're already on Canon. What "issues" are you concerned about?
A couple of points to consider though:
1. Why do you need AF on video? Are you trying to do telephoto with shallow depth of field on a moving subject that is moving slowly? Or is it wider angle with full depth of field? Maybe describe what your goals/needs are regarding video and having autofocus. While the 70D/80D/7D2 etc have AF with video, it's not nearly the same as AF for the still images. It's really only good for slow moving subjects if using telephoto focal lengths and some shallower depth of field. With wider angle and full depth of field, you don't even need AF since everything is in focus anyways. Something to think about.
2. 18MP to 24MP isn't much of anything for printing. You can print large prints of 30x20 from 10MP no problem. Don't get hung up on pixels. Printing is a total different affair, and scaling an image to be printed has a lot more to do with the processing software and prep that you do to it for printing, and the actual printing device/service. There's a whole different learning curve on being a printer of large size images. And having a 20MP image isn't high on that list. So again, don't worry about this. 18MP is more than enough for large prints. Also, what is large to you? 30x20 is large to me, for cost. But billboards are printed from even lower resolution images and are massive. You have to put things in perspective of size of print, medium used, and distance that it will be viewed at.
Very best,
