I just realized something. To slow a footage down I was always using the time remap feature in AE, but now I came across a tutorial about Timewarp effect and realized that it can do a much better (although slower) job. But I have one issue with it. With the time remap I can drag the right boundary of the clip to whatever I want, when with Timewarp I cannot do it. How do you expand your footage beyond its right boundary in this case?
Try applying a TimeWarp effect on a Timeremapped layer (but without messing with the time remapping)