Sorry, I wrote a nice long reply earlier and then my browser ate it.
As has been pointed out already by other helpful folks, that tactic is called "begging for a bite" unless you have very long forceps. Snakes can get very excited and stimulated during feeding, and sometimes their strikes go wild or they charge forward and aim for the hand rather than the mouse. You can run into the same problem with f/t prey on forceps with some of the really eager eaters, but the stimulus doesn't seem to be as strong with f/t prey. Live prey seems to trigger a whole different set of behavioral responses, and these are not responses you want your hands to be anywhere near.
The typical defensive strike range you have already learned to calculate and avoid is much shorter than the range of a feeding behavior bite. A hungry and highly motivated snake may move rapidly forward to nab whatever it thinks is the target, which will extend its effective split second strike range by a really scary distance that you may not be prepared for. If the snake gets your hand confused with the mouse, that's bad. I've had a few snakes actually swarm right up the forceps past the mouse and go for my hand because they were excited by the mouse smell and my hand was a nice, visible, warm, moving target. I always keep a small hook in my left hand to fend off this sort of thing, but it's a bit of a risky business.
One of the other reasons I like to feed f/t is that I prefer that my snakes don't have powerful, wild feeding reflexes. I like my snakes to move slowly up to the food, calmly open their mouths and take it in a leisurely manner. That way I can reliably feed them off of forceps with minimal risk and fuss, and worry less about violent feeding responses during handling.
I've gotten a number of my LTC animals habituated to the point that I literally place the food directly into their mouths with hemostats. All they have to do is open up. They don't have to do any chasing or even biting because they have gotten used to the idea that their dinner will be delivered into their mouths. This type of behavioral management definitely doesn't work with all snakes, and in fact can be very counterproductive if the animal has a strong enough feeding response to aggressively go after the prey item you are offering. Also you can really put a snake off its food by bumping it on the nose unless you have a very delicate touch. I don't have much trouble feeding my snakes in this manner, but some of the fascinated visitors who have watched this fun trick and asked to try with the next mouse seem to end up scaring the poor snake right off its food.
If you have an eager eater with strong feeding reflexes, it is generally a better idea not to let this snake associate any of the same stimulus you present during handling with food, for the obvious reason that you do not want the animal to come leaping out at you snapping for its dinner the moment you open the cage door. In practice this can be a bit difficult to maintain unless you have a separate food hatch.
I have a black boomslang whose bad table manners I can blame only on myself. It used to be cute and funny to tease feed her when she was little, so I did that. Now that she is approaching 5' her habit of launching out of the cage at me like a fanged mouse seeking missile as soon as I crack the door is somewhat less charming. She is a good tempered and docile snake when she is not actively seeking food. But her out of control feeding reflexes make her a much more dangerous snake than she would be otherwise. When she is offered a mouse on forceps it's not at all uncommon for her to try to swarm right up the forceps past the mouse, wildly snapping and striking at the larger moving target.
Small terrestrial viperids you shouldn't have much of a problem using the tactic you described if you keep the forceps at a near 90 degree angle. I have had small vipers try to climb the feeding forceps rapidly when they were held at a 45 degree angle or less. The problem you will run into is that the mouse may still be able to turn and bite. On the rare occasions I feed live and I see the mouse struggle and try to bite, I interpose a hook into the mouse's mouth and permit it to bite that while aiming to crush its skull with forceps. You can also try for a very tight neck scruff grip with the forceps that allow you to control the head, but this still doesn't guarantee that the snake won't do something stupid and put itself right in front of the rodent's teeth anyhow.
I once saw an indigo snake which had its tongue actually severed by a mouse bite. Pretty sad case; it would not eat on its own. I'd hate to have that happen to any of my animals, so I don't feed a lot of live prey.
Cytotoxic species enjoy the benefits of a more rapid pre-digestion when they envenomate live food, but a warm basking spot probably serves much the same purpose. Not enough studies have been done to definitively assess what a snake might be missing, nutritionally speaking, when it does not envenomate prey. However the anecdotal evidence suggests that as long as the animal is kept at a constant warm temperature, the additional aid to digestion isn't crucial.
. One time he struck a pinky and in no time started to swallow it. Of course the pinky was still wiggling and didn't die until a minute later.