1.2.1 Video element visual-only content has accessible alternative - Check #495 - composite check

495 - examples
- Fail 1
- fail 2
- fail 3
- fail 4
- pass 1
- pass 2
- pass 3
- Inapplicable 1
- Inapplicable 2
- Shadow 1
- Shadow 2
- Shadow 3
- Shadow 3
- Shadow 4
- Shadow 5