Ah, YouTube! The forum of the people!
I agree about the obvious safety issues, but you have to think about how many things start out as home-built prototypes like this. I don't know if this guy is planning on bringing this to market, or is satisfied with it 'as-is', but it is similar to automatic cut-off saws used in a number of industries.
Add a guard for the blade, some rollers and a measured stop for the logs, and a foot pedal to pivot the saw, and a guy could buck a lot of firewood in no time.
No picking up and setting down the saw, no pulling on the starter, no measuring, etc. Of course if he doesn't get around to the guarding stuff, it will probably be a short career.
Philbert