This is an example of an under ventilated attic. Note the crazy amount of cobwebs hanging from the trusses. This attic is fitted with roof vents, however, the style of vent is not the greatest design.
Towards the end of the clip you can see the vent style. It’s aluminum with the slotted grill.
A certain manufacturer’s attempt to make a more wildlife proof vent. In the end the result is the attic isn’t functioning properly, shingles are degrading prematurely, and eventually mould will develop.
If you’re being sold a “wildlife proof” roof vent, buyer beware. These vents can often make things a lot worse in the long-term.