Choose an appropriate storage device. Flash drives have many levels of storage capacity, from a few hundred megabytes to several gigabytes. Remember, video files are large. An average DVD movie will hold a little more than 7 GB of data, so even if you compress the video you'll still want a drive large enough to hold the number of DVD files you desire.
Locate your DVD's files. If you haven't already, insert the DVD into your DVD-ROM drive and open the DVD contents via My Computer, Macintosh HD or by double clicking the DVD's icon when it appears on your desktop. There should be one or two folders labeled VIDEO_TS, AUDIO_TS, or something similar.
Copy the DVD's files. Create a new folder on your flash drive identifying the movie or contents of the DVD using the "New Folder" option on your disk menu. Highlight the contents of the DVD and either drag the files to the folder on your flash drive or right click the highlighted files and select Copy. Return to the flash drive folder, right click again and select "Paste." Depending on your DVD drive's speed, copying the files can take anywhere from a few minutes to a few hours, so plan ahead.
Proof the files. Once copying is complete make sure all of your transferred files are playable. Open any DVD player program on your computer, select "File > Open > DVD media" (or DVD file) and select the DVD folder on your flash drive. If it doesn't play, copy the files again and retry. Do not begin copying another DVD until you have confirmed your files will play.