We were planning to do some internal Office training with the videos at eg http://office.microsoft.com/en-us/excel-help/up-to-speed-with-excel-2007-RZ010062103.aspx. Lo and behold, on certain machines the play button is disabled and refuses to function.
Browser is IE, but same phenomenon appears in other browsers as well. Problem does not occur with accounts with Administrator rights.
The odd thing is that an explicit installation of WMP 11 (on a machine with 12 installed) fails due to the presence of the newer version, but videos now play--but only for the duration of that one session. Log off and back on and you're back to square one.
A Microsoft web page reports a case where a corrupted policy seems to have caused this problem, which was solved by rebuilding the policy. However, in our case, the problem occurs with accounts belonging to no OU and with no applicable policy.
Unfortunately Microsoft has, for whatever reason, made it difficult or impossible to just download the video and play them in the WMP app.