How can we change the recording resolution format of my webinar

Hello,
I tried to record my latest webinar. When downloading the video on my Macbook, I see that the resolution is 1760x900 and it seems to be a new codec as I haven't faced this problem until recently. As a result, when I want to edit it with my software, it's getting way too heavy. How can I change this?? 

Manu thanks in advance...