Out of curiosity- am I the only one that is frustrated by the lack of support for non Nvidia cards? I would have thought that this will be a feature requested by a lot of folks.
What codec did you use for the .mov file?
What system are you on- Windows/Mac?
What OS?
What version of AE?
System specs can be helpful as well.
Remember to add the above info as it makes it easier to narrow down the issue.
From the looks of it it could be a compression problem or a videocard setting.
I got my money’s worth though from a Dell XPS H2C though- still have it after 5 years and with an updated card I am still doing work on it.
The Alienware I use at work is not bad- the newer ones have better specs.
You can always duplicate a layer, select it, select your reference edit in the Project window, hold Alt and drop over the duplicate layer to replace it.