2000 Slight Delay and a little humming sound and then slam when shifted to reverse.

willing to bet its mounts but sounds like it might be transmission issue because of the slight delay and humming.
Anyone ever experience this issue?

 

I have a 2000 TL and this would happen mostly if I parked on a hill and it was the transmission mounts.

 

Doesn't sound too good. is the torque converter making any whining sound? shifting in gears fine?