LM324 Pre-Amp For Mic (to PC) Not Working
Possible assembly errors aside, at timecode 0:36 the guy tries to calculate the circuits gain, and comes up with 500 (which would be ~54dBV). Given that a dynamic mics voltage range is round about 40mV (Possible peaks to 80mV or more) this should ring some alarm bells: 

\$500 \cdot \pm 40mV = \pm20V\$. 

Not possible with the present supply voltages from 0 to 5V. 

So what we need here is a much lower gain. Assuming some useful gain within the soundcard itself and to avoid clipping of the opamp near the rails, amplifying +-40mV to 1V seems like a much better idea, which leads to a gain of 25 amounting to ~2k resistor instead of 39k. 

For extra fun you can replace it by a 10k pot and play with it.

In the end where that guy shows the final assembly, I can also nowhere find any negative feedback, so either its on the back, or just a wire (making this a voltage follower then). 

What to learn from it? Don't just blindly build some youtube videos circuit without understanding it, especially from a video with 0 comments and not even 200 views... At least try to understand it by doing some simulation, e.g. in ltspice. It takes 10 minutes and gives you valuable information, in this case it could also give you the information that the frequency response of this circuit is nowhere near hifi ;)