I remember reading somewhere on how to increase your bench press by doing negatives that are heavier than the normal press. So if you could normally bench press 200 pounds, you would instead negative 250 and have a spotter help bring it back up. Does this actually work well in terms of building strength and muscle and if so, can all exercises utilize it?

I've used this technique for increasing pull-up strength. It is also good for starting to do pull-ups if you cannot do one.

The only thing I would warn you against is using it for more than 1-2 exercises per workout and every workout. It really hammers the muscles and can take twice as long to fully recover from.

It works, but use sparingly for optimal results - there is no 'silver bullet'.

Does this actually work well in terms of building strength and muscle and if so, can all exercises utilize it?

Negatives do work well in terms of building muscle and strength. There are many but let me suggest two that you don't need a spotter, they can get tired of helping. chins and pullups. Get a stool or bench that will allow you to start at the top of the move and then lower yourself slowly, very slowly. Then jump back on stool and repeat to failure. For my purposes, a chin is with a palms facing you builds biceps. Pull up is with overhand grip. Do both with shoulder width, no wide grips. And you could do same for dips for chest or triceps. Why slowly? to increase intensity when you don't or can't add weight.

Another way to apply negatives is in count, go slower on negative move in your regular exercises, say 3/5. Also if you do pure negatives, you should be able to use 10-20% more weight than normal.