I have a Dell M6600 laptop with Nvidia quadro 3000M, connected to a PC LCD monitor 3:4 via vga, and to a TV LCD 9:16 via HDMI. I use win+p to switch between the monitors (disconnect projector or projector only). Most of the time when I switch to the HDMI, the movie becomes low quality and choppy. The problem is inconsistent, and so far putting the computer to sleep, running a benchmark, or rerunning the movie after the monitor switch solved the problem, but not anymore. Now, only restarting the computer with the HDMI as the main display solves the problem.
It doesn't matter which player I use (vlc, smplayer, classic media player...).
Sometimes when I switch back to the pc monitor, the movie also become choppy on the pc monitor.