Note how the three tabs on the lens fit into the three slots in the fixture. The flexibility of the lens allows it to be squeezed enough to remove it from the fixture yet it's stiff enough to remain in place when it's not being squeezed.
The video shows replacing the older-style incandescent bulb with another incandescent one. Yours may have an LED panel or replacement LED 'bulb' but the lens/fixture design should be the same. If you look closely, you should be able to see the slots before attempting the squeeze-and-hinge-up move.
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