Avoid race condition when updating lyrics

Signed-off-by: Niklas Koep <niklas.koep@gmail.com>
Add is_video property to BlaTrack

Signed-off-by: Niklas Koep <niklas.koep@gmail.com>
A few PEP8 fixes

Signed-off-by: Niklas Koep <niklas.koep@gmail.com>