Every other Thursday, our instructor Ron Purewal (known on the Beat The GMAT forums as lunarpower) hosts a free study hall session, called Thursdays with Ron, where anyone can submit questions ahead of time and attend. Ron chooses a few themes from the questions he gets and goes over strategies for them.
In this session, Ron breaks down some Sentence Correction problems.
If you want more video explanation, you can find the full recording here.
If you want to view recordings of past Thursdays with Ron or submit questions for the next live session which takes place every other Thursday, you can do so here.