As
Hellhammer already hinted at change in file size, I will just confirm that by adding, that video DVDs use the MPEG-2 codec, which is not as space efficient as MPEG-4 codecs like Divx, Xvid or H264, which are often used for encoding content to distribute them in smaller sizes. Commercial video DVDs are often burnt onto Dual Layer (DL) DVDs, which can hold up to 8.5 GB (7.9 GiB) to store two to three hours of video (main title, extras, menus, ...), Single Layer (SL) DVDs can hold up to 4.7 GB (4.38 GiB), thus only being able to store 60 to 90 minutes of properly encoded video.
As MPEG-4 encoded video is only 700MB for 90 minutes of video, you will see an increase in file size as it is transcoded into MPEG-2 video.
Btw, your thread title is very unspecific and "violates" forum rules.
(see rule #3 under Minor Problems)
To edit your thread title, just click on the button on the bottom right of your original post and then click the "Go Advanced" button below your message.