Under Unix/Linux, you may have to protect the square brackets around the IPv6 address :

% vlc -vvv --ipv6 udp:@\[ff08::1\]

You may have to specify the output network interface :

% vlc -vvv video1.xyz --ipv6 --sout udp:[ff08::1%eth0] --ttl 12

where eth0 is the name of the network interface (under Linux the network interfaces are named ethX, under Mac OS X it's enX and under Windows it's X, where X is the appropriate number) .