Hi
".......When video clips are stabilised, they are moved to the bottom of the bin. ......... Is there a reason why they are moved?.."
It's all in the name.
Clips appear in the bin in alphanumeric order. e.g. Here, Clip 2-SP1-001.mpg (at the top) will be stabilized...

The stabilized clip now appears at the bottom of the bin as the name now starts with "Stabilized-"

Any other clips with alphanumeric names that fall after "Stabilized-" with not be moved e.g.TAPPING for SYNCH.mpg which would remain at the bottom of the list ....

This is easier to see if you switch to List view.... before and after....

Although this might cause inconvenience in some instances the workaround is simply to right click the stabilized clip(s) in the bin and select Rename from the option and remove the word Stabilized- from the name. The clip will then return to its original position. (Although you may not know it had been stabilized as it will have its original name again.)
Nat