Here’s another set of video explanations (one math, one verbal) of practice problems found in ETS’s Paper-based Practice Test for the Revised GRE, a PDF released by the test-makers themselves.
You can find the whole set of explanations for every practice problem here. Enjoy!
Math: Section 5, Question #6 on page 73 that begins, “O is the center of the circle…”:
Verbal: Section 3, Question #6 on page 52 that begins, “To the untutored eye the tightly forested Ardennes hills…”: