No need to reinstall again if you've done it. It's pretty weird for a video card issue to persist when you go from integrated to a real card. That would seem to eliminate motherboard or CPU hardware as being a culprit. CPU, RAM, Mobo, are still on the table.
The fact that both of your computers seemingly have the problem and are probably similarly configured makes a software issue even more likely.
Of course that assumes this is actually the same problem, and not two different problems with similar appearance.
For turning of the integrated graphics: I don't know what it'll be called specifically but you're looking for something to do with the integrated graphics. Might be called Intel HD graphics or something.
As far as codecs. For something that's all inclusive that you don't really configure go with
CCCP.
But you can also get along with madVR and LAVFilters, there are guides easily googleable.