Downloaded 5 episodes of a TV series & burned a DVD of it using the MacBook Air a week ago. I chose 480p MP4 as the download quality & each episode was around 285 MB.
It took a long time & the result, while watchable, was rather low resolution.
So tonight I repeated the process, this time using the iMac, downloading the episodes as 720p MP4, each one around 750 MB & burned a DL DVD of 7.94 GB. I then repeated the process but saving as a .dmg. Toast 16 was chosen as the assembly/burning app. Very effective.
Quite pleased with the result, which took about 20% of the time using the iMac & more streamlined processes than I'd employed with the Air.