The Mac-Forums Community Guidelines (linked at the top of every forum) are very clear, we respect US law and court precedence when it comes to legality of activity.
Therefore to clarify:
You may not discuss breaking DVD or BluRay encryption, copying, or "ripping" commercial, copy-protected DVDs.
This includes DVDs or BluRays you own. Even if you own the DVD or BluRay, it is still technically illegal under the DMCA to break the encryption. While some may argue otherwise, until the law is rewritten or the US Supreme Court strikes it down, we will adhere to the current intent of the law.
You may discuss ripping or copying unprotected movies or homemade DVDs.
You may discuss ripping or copying tools in the context that they are used for legal purposes as outlined in this post.
go to the exact frame you want in the timeline, then go to Modify>Make Freeze Frame. then i believe you can go to File>Export>Using Quicktime Conversion. then choose Still Image from the Format pop-up menu. and then save it wherever you want it