This method seems to work when you receive 403 Forbidden errors while downloading the video (it emulates the same headers that your browser sends):

Using Firefox, open Developer Tools using Ctrl + Shift + I, or click on the 3-line hamburger menu in the top-right (1.) > More Tools (2.) > Web Developer Tools (3.).

Go to the Network tab (4.), reload the page, find the appropriate .m3u8 entry, typically named stream.m3u8 or something similar (5.), right-click, Copy Value (6.) > Copy as cURL (7.).

Then paste the resulting cURL command into here: https://windyakin.github.io/curl2ffmpeg. Download and install the free, open source FFMpeg tool if you don't already have it, paste the resulting ffmpeg command into your commandline (you may have to add a .exe suffix, eg: ffmpeg becomes ffmpeg.exe if you are using Windows) and enjoy the video!