Thanks a million Simos! it works now!!
So my mistake was in this line lxc config device remove rosfoxy video0 unix-char path=/dev/video0 I shouldn’t have added unix-char path=/dev/video0
I also tested it with the connected motors by adding lxc config device add rosfoxy ttyUSB0 unix-char path=/dev/ttyUSB0 gid=1000 and now I can control the dynamixel servos.
I also started a question here, if you want you can write an answer there and I will accept it.
Thanks again!