A few years ago I was able to pick up the B5 20th Anniversary book at Phoenix Comicon, in 2013. The book is since then out of print, and will not be available again.
However, a multimedia edition is now available from B5Books.
Today (PST, I think) is the last day to purchase at the reduced price of $37. Tomorrow the fast response price will be the double.
If you have discovered Babylon 5 since the book went out of print, or you missed the print book for whichever reason, here is an opportunity to get the material in electronic form.
On top of that, there is some additional video material in the multimedia edition.
If you want to get it, you can go to
b5books.com and order.
Disclaimer : I am not affiliated with B5Books, but I have been a happy customer to many of their releases.
Have fun !