Storyful raises doubts about the authenticity of the horrendous video. A crowd-sourced effort from the Dish:

It looks fake. The victim was vocalizing after his mouth was covered with dirt and rocks. If it was real, we would hear choking sounds, or at least see the dirt around the victim move as his body goes into convulsions from coughing and gagging. The edit was sneaky – the last shovelful of dirt rearranged the stripes on the victims head gear, which was the natural point of reference for telling if the filmmaker swapped the "victim" with a dummy for the last ten seconds.

Another reader:

In the article you linked to, it says the man being buried "is then accused of carrying a camera to capture footage of Assad's forces to send to television networks". I'm wondering why they would do themselves what the victim was accused of doing, which was videotaping Assad's atrocities and releasing to the pubic. Doesn't make sense. Plus the voice seems dubbed in, and the jump cut, as you said, looks fishy.

Another:

I do a bit of volunteering for Syria Tracker (though do not claim to speak for them), so have seen a number of violent videos in the course of tracking human rights abuses. All videos like this must be taken seriously until definitively proven otherwise, but the video doesn't ring true to me.

A classic rule of forgeries are that they try to do too much in one fell swoop, like the infamous Habbush letter that purportedly showed that Iraq not only trained a 9/11 terrorist and by the way, here's the uranium yellow cake you wanted from Niger. From an intelligence perspective, if its too good to be true, it probably is. So a video depicting brutal torture techniques and verbal abuse while UN observers are on the ground might be a little too convenient. The Syrian regime is committing enough atrocities that fabrications aren't necessary.

That said, keep praying. The people of Syria are experiencing horrors like this almost daily. And thanks to blogs like yours that can get the word out.

Another:

The Daily Mail has a different version, with subtitled translation and no interruption at the :47 mark.