Need "For Dummies"-type explanation...

[PSidbury]

First of all, let me thank you for your patience with my post and also let me apologize if my post is not sufficiently explanatory.
Only because I am a super-rookie when it comes to the concepts of how video, movie files, etc. can be rendered/burned to a conventional store-bought 4.7GB DVD.
Also, please bear with my potential mis-use of industry-specific phraseology.
Hopefully, from context, you can decipher and aid in my remedial DVD-"authoring" development.
I truly need a "For Dummies..."-type explanation for my questions.

Okay... Using Sony Vegas Movie Studio Platinum 8.0, I have captured plenty of .M2T files from my Canon HV20.
I have also created several .wmv movie files in template "4.8Mps HD 720-24p".

So, now I have over 20GB in movie files that make up an entire project that we will call "Family Christmas", and want to burn it to a DVD using Sony DVD Architect Studio 4.5d.

My main concern:
Is there anyway to compress the 20GB project so it can be burned on the 4.7GB DVD?
Will Sony DVD Architect Studio 4.5d do it for me?
If not, is there a Best Buy purchased DVD "burning" software that will?

I want to retain at least a 4.8mps 720-24p resolution.

Secondary concern:
How large is the movie file on a typical "Top Gun" commercial DVD that I can buy at Best Buy?
I have no desire to pirate or copy "Top Gun", I just want to understand the difference between that physical DVD and the DVD-R I would use for "burning.
Meaning, is the "Top Gun" DVD itself a conventional DVD and Top Gun is compressed onto it, or is it a specifically-licensed DVD that holds 100GB of movie file and Joe Public has no access to it?

And all of this is within the context of normal DVD playback, not HD-DVD or Blu-Ray.

Again, thanks for your patience and "For Dummies..." type answers and explanations,

Paul

[PSidbury]

Okay, forget about Vegas Studio and DVD Architect for the moment.

I guess this is what I don't understand:

The Top Gun "widescreen" movie (which is about 2 hours) uses 8.5GB on a (dual layer) DVD. Am I correct in assuming that?

But yet I have a project rendered in MPEG-2 format that is less than an hour long and is 34GB large, and I am beginning to understand that (no matter what DVD authoring software I use) it cannot be compressed or formatted (and still retain the video quality that the Top Gun movie apparently has) onto one DVD.

Why?

How does that Top Gun movie that is 2 hours long fit on one DVD?

I understand (I think) the difference between commercial movies being pressed onto DVDs versus me "burning/lasering" an MPEG-2 file onto a DVD, but does pressing really make that much of a difference on how much video can go on a DVD?

Thanks again for your patience in answering my questions

[Chewy]

A 2 hour commercial movie would only be 5 gigs, extra sound streams, extras like director comments would make up the rest

Your home movies should do well at 4 gigs per 2 hours at standard 480, but at 720 hd you are exceeding the dvd standard

But yet I have a project rendered in MPEG-2 format that is less than an hour long and is 34GB large

Shouldn't be over 4 gigs for conventional dvd(or SD standard defintion vs HighDefinition)