Is there any way I can record a live streamed webcast?

There is a live streamed webcast that I really want to watch. However, I happen to have class at that time. I can go to the site using my laptop, but I don’t actually want to watch it in class because that would be rude to the professor.

Is there any way I can record the live streamed webcast so I could watch it later?

If it helps, the stream would be on LexisNexis, the law database.