[paulc]

First, I would tend to keep using a clone backup, but I can see usefulness for using Time Machine.

I frequently create very large movie files that I may need for only a half to 2 days. After I delete. So it is possible my TM backup may get quite clogged with these files. 2 questions...

How long does it keep a file that is no longer in the drive to be TMed? On the suggestion TM can be used to retrieve files one inadvertently deleted, one would THINK there is a setting for how many days to KEEP a deleted file, but I hear there are almost NO config options for TM...

Second, can one manually delete files ON the TM drive without screwing anything up?

[TETENAL]

It keeps files until the backup volume is full.

You can remove all revisions of a particular file from the backup by using the Action menu in the Finder while in Time Machine.

You could save those movies in a "work in progress" folder that is excluded from the Time Machine backup.