The file you sent me plays silent on my machine too. It does have an audio stream, but it appearntly has no sound in it.
So, it seems that sound was not fed to the recording during recording.
A couple of things to look at:
1. TV Configuration/Audio/Check "There is a physical audio connection...", and select the correct audio line (Line-In etc.).
2. Sound card hardware and driver. Have you recently made any changes? Do you have SB Audgy? Someone had a similar problem which turned out to be with Audgy, which was fixed by updating audio driver. The problem may be that the channel name enumerated in one context (i.e in Audio settings mentioned above) is not recognized in another context (i.e. in recording).
Have you tried time-shifting? How does it work?