Hulu Live Users

But, you can't always skip commercials even in My Recordings. Certain networks restrict your ability to skip commercials in some circumstances, even if it's recorded. What I've usually noticed is that stuff that is still airing on certain channels will not let you skip commercials, or will engage in other weirdness when you're trying to exercise your ability to enjoy what you paid for (commercial skipping.)

If it's been more than 24 hours since the original airing, commercial skipping is far more reliable on recordings. The non recorded versions seem to be treated as "on demand" which are far more likely to force you into unwanted commercial breaks you can't skip. Then it's time to mute and take a leak.