turning your rod on its side puts more pressure on the fish because it changes the angle on the rod to the meatier butt of your rod. I was at a seminar from a G-Loomis rep a few years back and that's what they were saying. There's also been several articles written in magazines about this very topic, (STS to name one). One other benefit of changing your rod angle is that pressure is coming from different angles on the fish and it has a harder time resting. For example, if someone was running around you trying to tip you over, you'd have to push back from all sides. If they just stood on one side and pushed on you, you could just lean back on that one side and use fewer muscles to fight the resistance.
One more thing. IMO, that fish was snagged. And a word of advice; if you think you are in an area where you can't safely land the fish, don't fish there. For example, why do people fish from the edge of a rock 20' over the water?
tight lines.