webinar screen and web capture

I would like a you to screen capture a webinar that i have time limited access.
I need this recorded in full screen with audio in a format that i can watch on my phone, ipad and pc laptop.
The webinar lasts for 3 hours and needs to be recorded in one full video.
I will email you a link to the webinar.
Keen to be advised on formats and best way to share the file.