Chris,
Your recording settings are probably fine. Just your render settings.
LESSON 1 Recording: You said you are recording at 1920 x 1080 x 60i. That is a great HD setting. HD recording will take about 13 gig per hour. That is it. If you have one and one half hours, it is 20gig.
You could record in SD mode, that will take up about 6 gig per hour. IF all you are doing is to record and upload to a web site, this may be an attractive option. The reason is to edit and render an SD file is much faster than the HD file.
If there is an option that some day you may want the footage for something other than uploading, you may want to do what you are doing, record in HD. You can downcovert for the web, and later use the HD for a bluray or something.
LESSON 2.
Rendering.
This is the process of producing an output file. There are an infinite number of compressions that can be applied as you render it. These can reduce the size and quality until you get the trade off you like. You will have to experiment. I am not familiar with the consumer editors like imovie, but there must be something that allows you to choose lower bits per second, or smaller image size, or less frames per second. That is both on the video and audio side.
LESSON 3. YOutube
About a year ago, You tube started a different approach and started allowing super large files like 10 to 20gigabytes to be uploaded to their site. You need a good internet connection and it might take all day to upload. Then, youtube will render it in various formats for you to best fit various output devices. They used to have strict rules, now they recommend that you upload the highest quality that you have.
Lesson 4. DVD players do not understand high definition. YOu mentioned that your hd video was 20Gig and how could it fit on a dvd. It can’t and a dvd player couldn’t play it if it could. That is why you have to put it on a bluray disk, which is 25gigabytes.
John
John Lenihan
LeniCam Video Productions
https://www.lenicamvideoproductions.com