It would be able to play HD videos just fine, editing is a whole other ballgame though.
In short, the A10 can be used to edit HD video, but I can't image it would be an overly enjoyable experience if you were doing it a lot.
A variety of factors come into play. The software used - the more cores it can take advantage of, the better (and buy a CPU that gels nicely). Intel's i5, i7 or Xeon offerings tend to be preferred for editing - but for significant editing. If this is a hobby or something you may do on occassion, the A10 would be ok.
RAM would be a big requirement too, 8GB would generally be considered the minimum for video editing. Depending how serious you are about the editing, 16GB wouldn't be a bad upgrade.
I think you'll be fine. The only "issue" would be the editing and exporting process. Puts a load on the CPU. But if you don't plan on doing a lot of background work while exporting a video, I think it will be fine. I mean, it will run a but slower than others, but I bet it won't be TOO slow.