This is in response about a recent mythvision podcast about John the Baptist, (excellent commentary by Mason on the Baptist BTW) and Masons brief comment on the Slavonic.
First of all I will have to say that this is an excellent video and I ended up agreeing with all of it except the brief commentary on the Slavonic. Admittedly Mason did put in a qualifier that he was not an expert in the Slavonic. Basically he said that the Slavonic was of no use in Testimonian Flavianum studies. I will now outline the reasons why this is wrong.
All scholars recognize that the Slavonic has been destroyed with Christian gloss as explained very well by Van Voorst:
“The Slavonic Josephus reflects the growing Christian tendency to excuse Pontius Pilate for Jesus’ death and to blame the Jews, even to the point of saying that the Jews themselves crucified Jesus. To make this point, the Slavonic version has to ignore Josephus’s original statement that Pilate crucified him….The Slavonic Testimonium uses the New Testament extensively at several points to develop its story.” .
But then Van Voorst goes on to say that the Slavonic does “not provide an authentic textual alternative to the main Testimonium Flavianum in the Jewish Antiquities.” 
So after he said that Christians were trying to bolster up the TF he fails to explain why they dropped his name “Jesus” and title “Christ”. That is my point that Van Voorst does not explain (or notice) if the Slavonic came from the textus receptus found in the MSS of Antiquities. Of course it is easier to explain if the Slavonic came from a Greek exemplar that existed before Eusebius fiddled with it. It would explain it perfectly if it came from an exemplar before Eusebius added the words ‘Jesus’ and ‘Christ’.
A number of Greek words taken over literally by the Russian, (Eg: igemon, metropolja, archierei, skinopigja, katapetasma, aramatji), which just shows that the Slavonic is working off an early Greek exemplar.. .
I never agreed with Eisler that it came from an Aramaic original, that’s where Eisler got it wrong but it did come from a pre eusebian Greek exemplar!
The Slavonic is so bloated, it is laughable. The most telling part of Slavonic is the fact that it says so much about Jesus except his name. This suggests that this particular line of transmission has preserved the notion that Jesus was not named in the original TF.
 Van Voorst, Robert E., Jesus Outside the New Testament, An Introduction to the Ancient Evidence, (Eerdmans, 2000), p.87-88.
 ibid, p.87
 Robert Eisler, The Messiah Jesus and John the Baptist, ibid, (English Translation), p.130.