Cleaning VirtualDub works, results in clean values in
HKEY_CURRENT_USER\Software\Freeware\VirtualDub\MRU List
(empty tag "MRUList REG_SZ")
There is a improved version called VirtualDubMod, which should also
be included.
It's MRU list is in
HKEY_CURRENT_USER\Software\Freeware\VirtualDubMod\MRU List
with the same content (MRUList contains the tags, e.g. "abcd" and there
are associated tags (a REG_SZ filename).
For test/assistance please contact me.