Watching videos helps, but you need to make sure you watch the correct videos.
Don't watch stuff like SoloRenektonOnly, Professor Akali, Heizman, etc, those guys make vids just for views, even if they do explain occasionally what they are doing, it's just random comments because of random builds, etc.
Watch full game commentaries on champs you play. Those guys will actually explain their though process. You said you play Talon, so try watching Aatrixx on youtube. He explains why he does things and why you shoul/shouldn't do them in the same situation or when you should do them, etc.
The problem with watching videos from guys like BeChallenger is that they don't explain why stuff happens, it's just the game, so you need to realize by yourself why they are doing what they are doing, and that's not an easy task, so just doing the same thing as them will help once in a while when the stars align, or as you said, you get some kills, but can't put them to use, since you don't know what to do with the lead, while watching full gameplay commentaries will have the guy explain why he is doing it, so you know how to reproduce and when to do it, and how to abuse the lead, in what ways, and that's what's more important.
Most low elo players aren't bad because they are bad in the sense of having bad mechanics, knowledge etc, but because they don't know what to do and they don't know what they are doing wrong. I confess, I also have that problem of not knowing what I do wrong sometimes, so I asked a diamond friend to watch my games every once in a while and tell me what I did wrong, what I can improve on, etc, so the thing you need to focus now is not on how to get better, but fixing what you are doing wrong. I know that is a bit counter intuitive, so let me put it like this:
Assume you have a line which is the "base skill level", to improve, you need to raise your skill level above that line, but right now, you are bellow that line, so you first need to get to and meet the base skill level, then focus on improving. If your farm is bad, try to practice farming in practice tools.
Beside that, I guess there is just one more tip I can give you, so follow this rule: ask yourself these 4 questions, in this order, every time you want to do something:
- How can my opponent hurt me?
- How can I prevent that?
- How can I hurt my opponent?
- How can he prevent that?
I also recommend you watch videos from SkillCapped on youtube, they explain a lot of things, so maybe it will help you.