New
#51
From your video https://www.youtube.com/watch?v=kd7b3gOwUuw :
It also appears that you may have the screens spanned so that both are actually one screen with the image on the right hand side. Otherwise if they were duplicated you'd see the same image on both. Check that setting in Screen Resolution. Try also using only the Laptop screen with Monitor unplugged.
It also looks like Steam is in need of a patch, which might explain why it is failing. So patch Steam to eliminate that.
But you say that other games do the same thing? Then it must be a display driver issue which could be that it is not powerful enough to support the external monitor or spanned image across both. So test it on each separately.
I've asked for assistance from those more familar with Steam games and external monitor on laptop even though I'm using one myself right now, but on a Core i5 with 8gb RAM which can support it.