I was trying to understand the logic here, and noticed the indirection
via a QualityResolver interfaces is pretty unnecessary. Just branching
directly makes the logic a lot easier to follow.

The `-999` sentinel value is a bit dumb, but java does not recognize
that videoIndex is always initialized.

Nice side-effect, the `Resolver` interface was completely unused and
can be dropped.

The function never returns `null`.

This should make the purpose of these functions more clear.