The microphone in your smartphone is, by design, intended for mono, voice audio. The opening itself is just a pin-hole towards the bottom edge so functionally it's for close proximity, not necessarily for picking up audio across a room. By keeping your expectations more in line with what you have to work with, you might not see this as an actual 'problem' but more of just the way things are currently. Maybe getting an external microphone will serve your needs?
https://www.amazon.com/s/ref=nb_sb_ss_c_1_18?url=search-alias=aps&field-keywords=android+external+microphone&sprefix=android+external+m,mi,232&crid=3LO12PEXIWZZS
Regarding the video you initially brought up, just curious but is this just some recorded video at some random event or is it something with more emotional significance like a baby shower?