There is a very considerable amount of wind in that video. Alot of sailors on this forum can right even the large beach cats in such conditions. Most larger beach cats won't turtle (float with the mast pointing downward) as the Hobie cat 15 does in the video. As such I really don't consider this video to be any proof of the Hobie 15 rightability. I know the Hobie 15 pretty well as I taught beach cat sailing on one for a season. They are pretty nice starter boats.

Others that are just as easily righted singlehanded are :

A-cats
Prindle 15
Formula 16's
Nacra 5.0 and nacra 500

personally I found the Hobie 14 to be relatively hard to right especially since it would turtle all the time, beach cats that have their masts float above the water are easier to right.

Also do not make the mistake of think that a small boat is always easier to right then a larger one. I found the Hobie dragoon and Hobie 14 to be among the hardest to righted boats when compared to say an F16 or nacra 5.0.

There are more factors important here then length alone. The only way to be sure is to just do it yourself a few times, especially in light to no wind as then it become much harder to right a beach cat even as the wind isn't helping anymore

Wouter