Velo Binding is when they fuse a piece (a thin bar, really)of plastic, paper-to-paper, along with your pages. So it fuses your pages together with plastic essentially. The fusing part is invisible, all you can see is that the pages are bound together.
It appears that you lose a little less than a half-inch of page with this method. If you go with the clear plastic cover option, it is all-around less flexible and thus it's tougher to spread the pages. I plan to use this method I will probably not get the plastic cover due to the lack of flexibility factor. This method is the more permanent method.
Initially I did not like this type of binding on looks alone. The plastic binding bar on the front and on the back are thin in width, but they are thick in depth, so they seem to sit a little high (binding-in-relief), and I didn't like that. But, weighing all of my options, the bar is not at all visible when you are looking though the pages, there is no visible seam in the middle getting in between the reader and your artwork, and it provides a good solid binding bang for the buck.
Tape binding is just that -- taping the book together with sturdy tape. You can see a black binding on the outside of the book, but no visible tape inside. I like this method because the book is very flexible and you can really see almost the entire gutter. There is also nothing coming between your eyeballs and the two-page spread. That is a big deal. Plus I just liked the feel of it.
The bad news is, it's really not very sturdy at all and it will fall apart pretty easily. (Boo hoo.)
I'm preparing my pages to print for the Velo binding right now, and adding a little space to the center pages so it prints correctly. I love everything about the tape binding except for the fall-apart nature of it, and unfortunately that is a deal - breaker this time around. I will likely experiment in the future, but for this round, I am going with the Velo with no clear plastic cover.