Comment 8 for bug 204413

Having that AVI file would be a huge help. Barring that...

==18231== definitely lost: 156 bytes in 4 blocks.
==18231== indirectly lost: 499 bytes in 29 blocks.
==18231== possibly lost: 8,801 bytes in 261 blocks.
==18231== still reachable: 399,407 bytes in 9,523 blocks.

Looks like we're not leaking that bad after all (at least, this case didn't catch this leak). Can you attempt to run your video thumbnailer over the file in valgrind and see if it causes this supposed leak? If so, then the bug is that your thumbnailer is the problem.