I've seen a few different vids like that - people backing trucks / trailers into the water ... not very well!
Boating & trailers (or lack of trailers!) can be pretty amusing.
A month or so ago I saw a guy launching probably a $50-70k 30 foot boat (from a trailer). He unhooked all the boat straps - including the BOW STRAP - before backing down the ramp toward the river... The boat rolls off the trailer before he's even close to the water. BANG!!! And there it is sitting on the concrete ramp. So what do they do? Back the trailer up to it and push it the rest of the way down the ramp into the river! SCRAAAAAAPE. (Then they pulled it out again and probably called the insurance company.)
That almost happened to myself when I had a boat... thank God I had a 4x4 at the time. I heard stories but seeing it made my night!!! Man did that ever make laugh!!!!!!