You are talking about a mp4 video you uploaded and played back as part of your webinar? Yes, that video will be part of the recording of the webinar.
If you chose to show a YouTube video during your webinar, then the YouTube video will not be part of the webinar recording. You can always download the YouTube video to your computer, then upload that mp4 file to your webinar before the webinar starts, and then if you play back that video, it will be included in the recording.
