GMAT Pill just posted 110 video explanations to 110 sentence correction questions on the GMAT Practice Pill Platform.
Each of these questions are labeled with the percentage of users who got them correct. You can contribute your answer by selecting the question and inputting your answer and clicking Submit.
Alternatively, you can click "Show Answer" to display the video explanation and correct answer. Each time you answer a question, the system records your response into your online workbook.
When you return to the sentence correction tab page, you'll be able to review which questions you got right and which GMAT questions you got wrong.
After clicking "show answer" the video explanation will appear below the question. Simply scroll down the window and you will see the video explanation autoplay. Most video explanations are around 3-6 minutes long. And yes, every single one of the 110 questions has a video explanation.
Some video explanations are available up front without a need to login. But most questions will require you to login to view the explanation.
If you do not have a paid GMAT Pill account, you can still look at the questions and participate in DISQUS comments about that question. You would need to upgrade your free account in order to view the remaining video explanations.
All of these questions and GMAT videos for GMAT sentence correction questions can be found here.