Apple Final Cut Pro 7 - Manual (Page 729)

Media Limit
This message indicates that one of the sequence clip items you are trimming no longer
has enough media to continue trimming. This happens even though other clip items in
your selection still have additional media.
Media Limit message
For example, suppose you select the Out points of clip items on tracks V1, A1, and A2
and then roll the edit points to the right. If the clip item on V1 is shorter, a “Media Limit
on V1” message appears. You cannot roll these edit points beyond the media limits of
any of the clip items.
Clip Collision
This message appears when you try to perform an edit that might inadvertently cause
unselected clip items to overwrite others. This usually happens when you are trying to
perform a ripple edit on one track, and unselected clip items on other tracks cannot ripple
because there are other clip items in the way.
729 Chapter 45 Learning About Trimming Clips