While there are some valid points, no-one has mentioned the most important. YOU NEED THE RIGHT PLUGS.
"RJ45"* plugs come in different types. Historically, they had a couple of points on the back of the contacts designed to pierce the insulation and go in between the strands of stranded cable. If you use these with solid cable then the points will either pass down one side of the core and not make a reliable contact, or will cut the core that will mean an even less reliable contact.
Plugs for solid cable have the points offset to go both sides of the solid core. I've used plugs with 2 or 3 points. The 3 point ones have the centre contact offset the opposite side to the others, which I think (no evidence, just an engineering feeling) is better than the 2 points.
For good measure, there are different plugs for stranded round and stranded flat cable. For round cable, the entry is a shallow "D" shape; for flat cable, it's a parrallel slot.
As others have said, don't use solid cable where it'll be flexed. But for something like a fixed camera to fixed DVR or switch then it's fine. Actually, signal wise, solid cable is supposed to be better.
* Being pedantic, none of us actually use "RJ45". We use 8P8C modular plugs (with some IEC number I can't remember).
"RJ45" is a combination of the 8P8C plug with a specific connection of phone line. Actually, it turns out RJ45 didn't even use the same connector
Registered jack - Wikipedia - https://en.m.wikipedia.org/wiki/Registered_jack