...ok
I just looked at the xnxx vid you posted here,
it's an mhtml format video.
I've tried to solve this problem before
and have reached the conclusion that only the websites
that use mp4 format videos can be downloaded easily.
The sites that I use are, (sign in required).
SpankBang (the best site, and with choice of resolution)
XVideos
PornHub
Motherless
Possibly mhtml vids can be made to work but
that's beyond me.
If you don't want to sign in then you'd need to talk
to a web designer or programmer to look inside your
browser,(right click > INSPECT)
where , I THINK, it's possible to locate
the actual video without all the web packaging.
But i've given up that little software nightmare,
and stopped chasing the difficult in favour of
grabbing what comes along by chance.