Like Terry i am no k-meleon programmer either.
This is not a k-meleon bug; It is a windows bug.
http://gemal.dk/blog/2003/08/07/use_windows_media_player_9_in_mozilla/
A solution for player 10 that can be inluded in AX versions.
Gemal´s page also shows that You do not have to hand edit registry. AFAIK a file could be passed out with k-meleon ax.
For this create a file with name k-meleonAX.reg and write into it.
REGEDIT4
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MediaPlayer\ShimInclusionList]
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MediaPlayer\ShimInclusionList\K-Meleon.exe]
save it and ship it with ax version; later the users that need it can click on it.
(Note: This reg file/alteration is not needed by an initial k-meleon because that assumes that You use the safer netscape plugin type: players, readers ....)
BTW: To use Player6.4 selective after changing the registry key, just use a k-meleon.exe that is renamed.
Plus IMHO the whitelisting that Fred does is more safe than he thinks/trusts or writes in forum.
AFAIK You can use the player all the time when surfing. Because k-meleon can not use other activeX controls that are not mentioned in the whitelist. So You only have to watch for warnings about bugs in media player.
Fred´s switch would be needed/used when You changed from whitelist to security step/level model of activeX support. I do not recommend to use the later in the wild net but only on sites that You trust. For details on settings e.g. how to white-list sites look into activex.js (i assume that its the same as with 0.9.12?).
You may need the later stepwise kind of activex support to use plugins which names You do not know. But better try to find out the names and whitelist them!