Here’s a recipe:
Duplicate the layer, and disable the copy (click the eyeball):
this original will remain there for future reference, if you do decide to tweak the layer some more within this context.
On the duplicate, visible one: do a precompose, ‘move all attributes…’
caveat: if you’re using expressions that reference other layer’s properties on this layer: you should change your expressions so they keep working in the precomp
Now, while having the precomp selected, do Composition-> Prerender.
In the Render Queue, hit render.
After Effects will render the precomp and replace all occurances of the precomp with the movie (or pict sequence)
You can also twirl open “output module” in the render queue before you render and change the setting “Import & replace usage” to “Set Proxy”. Check the manual for the difference between those two options.
Most importantly, if you use proxies, be sure that your Render Settings are set to use those proxies if that’s the idea…