I think the problem is caused by your audio (voice) being just too loud. You seem to be experiencing "digital clipping", where the peak level of the audio is above the maximum that can be recorded, normally measured (for digital) as 0dB.
You need to either "shout" more quietly or, somehow, reduce the input level of the audio. I assume you are using the built-in mic of your computer? From your video I can't tell whether you are using any sort of head-worn mic, or similar, but you need to reduce the Recording Level of your mic in the Windows Volume Mixer.
OR, less likely I think, the actual mic has developed a fault. In which case you might need to consider purchasing a replacement.
. . . . the actual mic has developed a fault. In which case you might need to consider purchasing a replacement . . .
From what I see and here, assuming the audio is truly in sync - is the buzz appears just after the loud audio (high sound pressure level - SPL).
This could be caused by the high SPL displacing the microphones the diaphragm / element so that it is 'sticking' which then gives the buzzing effect as it recovers itself once the high sound pressure level has gone and has Jeff has said may be damaged.