What do you mean when you say, "I have copied and pasted the clip."?
You shouldn't have to copy and paste anything if you right clicked your footage in Premiere and hit "replace with After Effects Composition." That footage will become a linked composition with After Effects. Then any changes you make in AE should show up in Premiere.
I assume if I "replace with After Effects Composition" I can still undo if it doesn't come out alright. Yes?
I am not completely sure if you can go back to your original footage. You can sureley undo it right after you have linked the composition, but if you saved your project, closed and re-opened it, I don't know how you would go back to the original.
In the past, there have been a couple times that I have run into problems using Dynamic Link between AE and Premiere. Therefore, if I am about to link footage to AE, I will copy the orginal footage and put it on a track in the sequence that isn't visible. That way, I still have the orginal in case I want to go back or if something screws up with Dynamic Link.
I hope that helps!
It's all messed up.
I stabilized the footage on AE.
I went to check it on Premiere before hitting "Apply" to find out that it had deleted the video effects (brightness and so on).
I tried to undo the whole thing in Premiere and AE but it doesn't revert to the edited Premiere footage.
Am I out of luck?
Unless you're saving versions of your PPro project you are out of luck. Dynamic link is really for processing shots in AE before you do anything else. It's the only workflow that makes sense when you've been in the business for a while.