If you are using Plextor to record from Wj_HD300A series DVR, plextor does not convert it for ordinary media players, when you perform the disk ejection procedure, a viewer is also written to disk for playing the recorded file.
Moreover there is no need to format the media (CD/DVD) while using Plextor, the CD-RW and DVD-RW can be format.
The next, it is written in the manual that you can backup to CD/DVD or DVD-RAM only, no USB Flash writing is possible (see Copying section in manual.
Regards,