Well most popular RAM brands are actually fairly equal. Also for video editing you should try Windows Movie Maker. It gets the job done.
And the games you wanna play seem fairly easy to run. For GPU I'd suggest a 750 Ti. Mongius might prefer the 950 but the 750 Ti can handle the games you'll be running for like 60-70$ cheaper. As for CPU you said you wanted Intel and it doesn't seem like you need a Quad-Core so a 4170 should work fine for your build. Don't forget to do your own research about our suggestions.
RAM I suggest Corsair. G.Skill would be fine too if you prefer it. Vengeance though not Dominator. I'll link the RAM here. I'll also post a part list here along with the reasons for each part that was chosen in the list. Gimmie a few mins. Also your welcome in advance ;)
P.S. Does 500$ include peripherals?
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Well if Pentiums then I'd say the G3258 is better than the one you mentioned. I forgot to ask if you'll overclock though. If you don't plan on overclocking with your CPU then the 4170 is better. It's what I'm buying for my first desktop build. Our builds are fairly similar which is why I wanna help you since I already heavily researched this price range for months with everyone's help here as well. If you will be overclocking though then maybe you can go for a G3258 but we might need a slightly bigger cooler. And ok thanks removing the disk drive from the list. Adding the list soon.
PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i3-4170 3.7GHz Dual-Core Processor ($116.96 @ NCIX US)
CPU Cooler: Cooler Master Hyper T2 54.8 CFM Sleeve Bearing CPU Cooler ($11.99 @ Newegg)
Motherboard: MSI Z97S SLI Krait Edition ATX LGA1150 Motherboard ($92.98 @ Newegg)
Memory: Corsair Vengeance 8GB (2 x 4GB) DDR3-1600 Memory ($35.99 @ NCIX US)
Storage: Samsung 850 EVO-Series 250GB 2.5" Solid State Drive ($89.98 @ OutletPC)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($45.89 @ OutletPC)
Video Card: EVGA GeForce GTX 750 Ti 2GB Superclocked Video Card ($99.99 @ Newegg)
Case: NZXT Source 210 Elite (Black) ATX Mid Tower Case ($44.99 @ SuperBiiz)
Power Supply: EVGA 500W 80+ Bronze Certified ATX Power Supply ($34.99 @ NCIX US)
Case Fan: Corsair Air Series SP120 High Performance Edition (2-Pack) 62.7 CFM 120mm Fans ($21.99 @ Amazon)
Total: $595.75
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-05-06 02:17 EDT-0400
CPU: Great CPU. Best i3 out there.
Motherboard: Basic motherboard. Nice black and white color scheme. Allows overclocking for future upgrades.
RAM: Basic RAM. Will work great. Good price point.
Storage: Reliable 1TB HDD for mass storage. SSD for games. SSD size can be lowered to 120GB to lower the price.
GPU: Good basic GPU. Should be able to run most mid-range games fairly and games like LoL and CS:GO with good framerates.
Case: Basic case. Enough ports, fan slots and features to accomodate all basic needs in a case.
PSU: Good reliable PSU. Some space for upgrading. EVGA makes good hardware.
Note: Hmm I thought writing a description like this would be harder than this. Well thanks for the practice for when I make one for my own build. Hope you liked it! ;)
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Oh btw sorry I went 95$ over your budget. If that won't do we can downgrade on some areas perhaps but if that extra 95$ is okay with you then this is a great build for gaming, video editing and everyday tasks such as writing and watching YouTube.
Don't overspend man. I heavily updated my sticky this night with informations about why you should spend money on specific parts. (took me two hours), so you might check it out. *hint hint hint*.
To sum this up, the Z170 doesn't fit with the i3. You can not use them together because Z170 is a 6000 series motherboard, not 4000. Also it supports DDR4, not 3. However you bend it, they will NOT work. You will have to buy a B85 board, which is like 50-60$.
HDD : I prefer Western Digital over Seagate because they break much less.
SSD : Hey man you forgot something there.
GPU : Totally fine, but you can increase it.
PSU : Also a nice one, but overkill for that build. Your computer will consume 250-300 watts at max, so a 400W PSU is fine too.
Case : I actually built with it twice for friends and it was hell. I hated it, working with it is an absolute pain, even when you are experienced with it. The walls are jiggely and mushy, you can press them in with your pinky. I'd really be scared to hold something in there, a cardboard box could be safer. Also the bundled PSU is more dangerous and explosive than ISIS.
So my changes would be these :
CPU : Intel i3-4170 2x3.7Ghz
CPU Cooler : Cooler Master Hyper TX3
GPU : Nvidia Geforce GTX 950
RAM : Kingston HyperX Fury 16GB DDR3-1866
HDD : WD Blue 1TB 7200 RPM
SSD : Sandisk SSD PLUS 240Gb
Motherboard : Gigabyte GA B85M-DS3H mATX LGA1150
PSU : EVGA 400W ATX
Case : Fractal Design Core 1100 mATX
http://pcpartpicker.com/p/6MsmVn
This is 550$ and even stronger than your current suggestion. You can also downgrade the SSD to 120GB to save some moneys, just dont miss it.