I don't know what types of WTV recordings you have, but if you record through a cablecard-enabled tuner (e.g. Ceton, SiliconDust HD Prime, Tivo, Hauppauge DCR, etc.) you won't be able to play any copy-protected WTV programs through anything other than WMC.
Absolutely false.
All my .wtv recordings ( made with SiliconDust) play perfectly through Mezzmo.
They even play with PS3 Media Server, but the audio is out of sync - hence the Mezzmo program.
I may be wrong, but as far as I know...
HD Homerun is OTA/ClearQAM, whereas HD Homerun Prime also supports cablecard for copy-protected content. Using the SD external tuners with cablecard allows the recording by WMC of copy-protected content delivered via your cable system. And it also requires WMC and cablecard to do the recording/viewing and also to play it back.
WTV recordings can therefore be copy-protected, or copy-freely. Copy-protected requires an installed cablecard to decrypt and play back, and only WMC has the DRM ability to use the cablecard.
I don't believe there is any other software (neither players, nor editor software like VideoReo) other than WMC that has the ability to use cablecards and decrypt copy-protected content for playback. And you can't even play copy-protected recordings made on one Win7 system on a second Win7 system. You can't even play copy-protected recordings with Windows Media Player on the same system that had Windows Media Center do the recording! Only WMC can play back its copy-protected recordings, either on a connected monitor or through an extender on the LAN (to an HDTV connected to the extender).
In contrast, copy-freely content (either OTA/ATSC or ClearQAM from cable) doesn't require a cablecard to play/record/playback... by any software. You can use many media players/editors to view, record, playback, edit, etc. No restrictions on copy-freely content. Play it on other machines, play it with WMP or other software, burn to BluRay, etc. No restrictions on copy-freely content. You can do none of this with copy-protected WTV content, other than playback (on local monitor or through an extender) through WMC on the same Win7 system that did the recording. And the encryption key is even "time-sensitive", so if you do a "system image" restore from an image taken last week, you will NOT be able to play back copy-protected WTV recordings made THIS week (i.e. after the date/time of that "system image", since it used a different time-based encryption key)... even though it is the same machine and Win7 system. The encryption key from the system image as of last week's backup will not work for recordings made after that system date/time! That's DRM, and that's WMC working. No other software can work with DRM.
Now, are your WTV recordings copy-protected? Or copy-freely? BIG DIFFERENCE.