the ISO file is actually a CD Image in file format. The easiest way to determine what is on it is to mount it with a Virtual CD program. Or you can look at the file contents.
Here is the Specifications for ISO files
http://users.telenet.be/it3.consultants.bvba/handouts/ISO9960.html
After you are able to determine what information is on the disk then you can determine if there is video information on it by finding out what the contents of those files are.
That is a much more daunting task then just determining the file structure.
This specification file will only define ISO files. Other cd formats will need to be read using their own Specifications...
You can determine if the file is of type ISO using the header data
Here is a Stack Question explaining in a little more detail.
Using .NET, how can you find the mime type of a file based on the file signature not the extension
EDIT
Looking into the Mime type thing a little more reveals that Microsoft will have to have a registered mime type for that header data. It may not know that it is an ISO and may tell you application/octet-stream If this is the case then you can instead use your own judgement with the same first 256 bytes. Determine some things that tell you that it is an ISO file that you can handle. Usually you can tell what type and version a file is with the first 20 bytes or so.