Understand that companies like Fox and CBS don't actually produce the DVDs. In fact, CBS doesn't really own anything, and is just the broadcaster -- although it may have to sign off on certain rights. Fox has an entertainment wing, and owns shows, but isn't really in the DVD business. It's in the content broadcast and ownership business.
Note: I use "DVD" here, but it refers to anything physical -- tapes, Blu-ray, Laserdisc, etc.
Another company is contracted (or as in the case of companies like Mill Creek, they approach the content owner) to acquire and distribute the content. That company may or may not do it's own work either, outsourcing each piece to others -- capturing, editing, authoring, creating artwork, pressing (like burning). It's not any different from home workflow that avoid all-in-one software.
The recessions of 2003 and 2008-2009 really hurt the world of DVD media -- everything from manufacturers to suppliers to replication companies (pressers). A lot of companies are gone now. And like other aspects of DVD media, it's almost a shadow industry that can be hard to track.
The authoring aspect isn't too hard to trace, as the authoring houses (which can be full dub houses that handle their own DVD replication) almost always leave their mark on discs. After a feature or full TV show has played, one of the on-screen logos will be for the company that produced the disc. Sometimes its even on the DVD box/case art itself. From there, you can contact those companies and find out where their DVDs are pressed, then the presser can give more details on the disc supplier (or manufacturer if the presser doesn't use a middleman supplier).
Somebody like Fox or CBS is probably entirely removed from the equation, and the specs for blank media is no more than a line entry on a contract (of at all). Some DVD releases use obviously good quality blanks materials, while others have subpar materials (for example, Mill Creek and other budget shops). You'd have to talk to the company contracting with Fox/CBS/etc to find out what a typical contract includes here.
For example, on my desk right now, is a Critereon release. In the case of Critereon, the studio owns the work, Critereon contracts to release it, and they may (or may not) outsource part of that process. I think Critereon primarily focuses on the encoding and possibly the authoring -- not the pressing. They likely outsource that. So see who does that, and with what materials.
It's completely different from the world of DVD burning! Pressing in not buring! The same is/was true of VHS, Laserdisc, Blu-ray disc, etc.
When the discs are sold, the studio gets a residuals cut, and the releaser may get a cut. The outsources work on a project fee basis, either hourly or flat rate.
Realize I was an outsourcer for a studio for about 5 years there, before I was forced to leave the business (health reasons). In fact, that studio was interesting, as it would both release its own content, and release the content of others. There were lots and lots of middlemen. Securing rights would sometimes take 2-3 years, and producing the discs may take another 6-12 months -- especially when the content was rougher and in need of restoring (which is where I came in).
Is that enough info?
What level of study is this for? Junior high, high school, college undergrad, college grad?
Trivia: I know a DVD/Blu-ray artist in UK -- a friend of a friend that I follow on social media. All he does is artwork for commercial interests, mostly cartoon disc releases, and his Facebook feed is often a showcase of his newest work. His art is then used by somebody else (releaser? authoring house?) for the final layout and logo adds.