Video Reviews : ****Excellent***Good**Fair*Poor : <i> Recent releases, reviewed by Times critics.</i> : Comedy

* 1/2 “Dorf and the First Games of Mt. Olympus.” J2. $29.95.

Played by Tim Conway, Dorf is a toga-clad dwarf stricken with a severe case of Murphy’s Law. In the year One this pint-sized loser comes up with the idea of the Olympic Games. But everything goes awry when he enters a variety of athletic events with his two pea-brained assistants. Within a mere 35 minutes Dorf gets flattened in the boxing ring, pole vaults into quicksand and gets physically abused in a myriad of excruciatingly unfunny ways. The only thing missing is the old slip-on-the-banana-peel routine. What’s most offensive is that, as in its predecessor, “Dorf on Golf,” many of this tape’s laughscome--if they come at all--at the expense of the lead character’s midget status (Conway is given awkward, stump-like legs).