The Historical Jesus

[Sheldon]

On the issue of Gospel authorship here I have found a video which summarizes things in a way that is fairly easy to follow.

https://www.youtube.com/watch?v=C7s22DR9gaI

Not interested thanks, I know what anonymous means, and I understand the importance of a primary source when validating historical material, as I explained above. 

First of all, most histories at this time did not have the author refer to themselves within the body of work itself. 

1) Not true, I gave you an example above of contemporary biographers for Alexander the Great. 
2) A false equivalence, as historical records are generally not making claims for supernatural magic, from unevidenced deities. 
3) The gospel myths are anonymous hearsay, which is pretty poor evidence for anything beyond the most trivial events. 

There were early church fathers, such as Papias, who would refuse to acknowledge a writing as scripture if an author could not be identified. He ended up identifying all 4 Gospel writers. We also have some fragmentary manuscripts which identify some of the Gospel authors such as P 66 and P 4. We also have other 2nd century sources such as Clement of Alexandria as well as Irenaeus who both were able to identify all 4 Gospel authors. And, for some reason, all of these sources point to the same 4 names being assigned to the same four Gospels, exactly as our modern Bibles attribute them.

The earliest copies are all unauthored, what you're talking about is subjective speculation. 

If the Gospels were anonymous then we would expect there to be a wider amount of speculation around who wrote them. Do you have any evidence in favor of a different author possibly being responsible for writing any one of the 4 Gospels?

There is no if, the earliest copies are all unauthored, this is an accepted fact. Speculating on who might have written them won't change this.