The joke here is that Obama is keeping the often polarizing figures of Sharpton and Jackson at arm's length. I found it funny, but apparently some people found it to be racist. You can see some of that discussion here on this DailyKos diary.
The people complaining are reacting to some of the symbolism in the video, specifically the electric collar. Robert Smigel ought to be cut some slack here. I've seen him use all sorts of similarly silly devices in a number of his cartoons to exaggerate a point. Maybe it's tasteless, but I doubt there is any racist intention or influence. Perhaps the real problem is that it could be misinterpreted as racist.
But I believe there is an important difference between something that is racist and something that can be misinterpreted as racist. Just as there is a difference between bigotry and insensitivity.
Is the cartoon insensitive? I suppose so, because the author apparently offended the sensibilities of a number of people. But I also thought it attempted to make an important point in satirical form. I strongly suspect that some of the negative reaction to this cartoon is masking concern about the accuracy of the underlying message.
"The Obama Files" Video Description:
Obama is at a campaign event and Jesse Jackson shows up. While Michelle distracts the press by vomiting, Barack takes Jesse into a broom closet for a secret meeting where it becomes obvious that Obama has been sending him on wild goose chases to keep him occupied during the campaign. he sends him off to an African nation (which may or may not exist) and tells him to bring back some sort of rare zebra.
Later, Obama is being interviewed by Brian Williams. Al Sharpton shows up, having returned from a wild goose chase of his own. An Obama aide tranquilizes Williams to give the senator a moment alone with Sharpton. Barack tells Sharpton to meet him to the next speaking event, and gives Al some special jewelry which turns out to be one of those electric fence-type collars. Once he puts it on, he can't get near the speaking event.
Sharpton and Jackson decide to masquerade as podiums and crash the event, replacing the real podium. But Obama is ready for them with a trap door. In the end, they are spirited away (along with Bill Clinton and Chuck Norris -- refugees from other campaigns) to some vacation destination where they will trouble no one. And they sell their story to the Wayans brothers.