The problem with the term DVD is that it can be applied to to distinct entities:
The physical medium (i.e the 4.7 GB optical disk)
The actual content of the disk.
To be classed as a DVD in the latter case, the content of the disk has to follow a distinct file structure, and this has to be placed there using a soem sort of DVD authoring tool.
However, the physical disk can also be used to store data files.
If you simply copy a file such as an mkv, mp4, wmv, or avi, to a DVD disk, the result is a data disk. Assuming that you have suitable software on your computer (such as VLC player or the like) you'll be able to play these data files on your computer. However, unless your DVD player is a later model, which can read data disks and has support for those file types, you won't be able to play the disk in a DVD player.
The fact that you disk also contains a pdf file, would suggest that it is formatted as a DVD data disk, not a DVD video disk.