Well, I guess my ignorance on this product is showing.
I didn't know you somehow told WMC that the analog input being provided was actually for a channel. And even then, how would WMC know that the content was "copy protected" since I thought that was only possible when the input was digital, since that's where the 5C flags are buried in the metadata.
Before using WMC I was using BeyondTV, and recording S-video analog input to the ATI TV Wonder card I was using at the time (which also had a single OTA/ATSC tuner for roof antenna coax input which was also handled by BeyondTV). The S-video input was analog from my DirectTV non-HD satellite receiver. So I could record either (a) OTA/ATSC local network broadcasts from roof antenna, and (b) D* satellite broadcasts, no matter whether premium or basic cable channels, in 480i SD.
Everything was encoded to MPG for recording by BeyondTV, with the OTA/ATSC recordings being exactly the MPEG-2 HD digital ATSC content recordings bit-perfect, whereas the analog S-video input from the D* receiver was simply "encoded" (in "best quality") by the ATI hardware/software as used by BeyondTV in support of S-video input.
There was NEVER an issue of playback of anything recorded to MPG by BeyondTV. All OTA/ATSC broadcasts are "copy freely" in their 5C flags, and S-video analog input doesn't carry any such copy protection flags since it's analog.
I just assumed that your component video input to your Hauppauge card would work the same way, but then I was not using WMC to do my old recordings. I was using BeyondTV.
Again, I don't know how this works, and I'm honestly very surprised that there is anything at all that could possibly be known about the component video input coming from what may or may not have been a copy protected program being delivered simply as "external line-input via component video".
I'll have to plead ignorance here, as I have never used this product and was really just speculating based on my own experiences.