@EmmaFurtado - Could you elaborate your requirement a bit? We have implemented the live webinars (i.e. the YouTube/ Vimeo videos) on the community with the ability for the users to watch the event live and comment on it without the page being reloaded. It is a very cool and neat implementation. Let us know if you need more details about this or PM me for updates.
I hope this helps.
@EmmaFurtado -- Once the webinar has been created in BrightTalk - you should be able to embed it in the Lithium Community regardless of it being started or not. For example, you could create a blog or Knowledge Base article, and embed the webinar in readiness for the event to start. At the time of the scheduled event, members can then watch it live directly within the community.
I am fairly certain that BrightTalk functions similar to a google hangout or YouTube live event in that you don't have to update the code post event. In other words, users can watch the recording on demand after the event.
I would first test to see if the Video tool in the WYSYWYG editor supports BrightTalk links. If not, you can use the html editor to incorporate the embed code. The code should look something like this...
Not sure about the registration piece 
But would hope that the folks at BrightTalk can provide their own recommendations.
Hope this helps!
