I have an HP Pavilion dv7-6199us with an Intel Core i7-2670QM and an AMD Radeon HD 6770M. Whenever I try to boot from a live USB drive of LMDE (x64), XFCE or GNOME, it hangs right before loading the desktop.
I occasionally can boot from a live usb fine without this problem, but this is what happens most of the time. I notice when I can't boot, (in the video) those 25 or so very similar error messages that display quickly are shown, while when I do boot fine, they are not (hopefully you can figure out what I mean).
I've had other USB problems with LMDE too, including when making a live USB from Unetbootin (on in this case I was trying LiLi), my computer will not recognise the USB drive as a bootable device unless I turn on Floppy Boot in the BIOS, when then it will only boot with Lili. I could only boot properly every time from USB when using dd to make a live USB of the Linux Mint KDE image. Maybe it would be beneficial to make LMDE iso's hybrid iso's too?
If the above paragraph is confusing or not useful, ignore it, what's happening in the video is more important. I think this might have something to do with my ever-despised AMD card, not sure though.