[Florian Gintenreiter]"The Clip "XXX" can't be linked to the media file "XXX" because the timecode extents do not match."
Always a good one.
It could be a slight discrepancy between posted and actual frame rate, ie the clip is advertised by Quicktime as 23.98, but its really 24.000. Your clips may not actually have time code, or it may be a different code altogether, like some kinds of Long-GOP codecs and a synthetic count.
Very often, if those clips have been imported into the media pool, you will be able to hand-conform them into the timeline, and almost 10/10 times they will fit so perfectly, you will seriously wonder what could possibly be different about the time code extents.
"I always pass on free advice -- its never of any use to me" Oscar Wilde.