there are fairly good China-specific Linux distros (that comply with chinese regulations) . Like Ubuntu Kylin - http://www.ubuntukylin.com/ and Debian Deepin - https://www.deepin.org/en/
Simply downloading Debian from a valid mirror isn't the same.
Red Flag was made mandatory in a lot of public access points like cyber-cafes.
What the creator of that video identifies as 'spyware' was telemetry of the app store because it was built with web tech (cnzz, the chinese equivalent of google analytics). Calling it spyware given that we're talking about Chinese users is clickbait of the worst sort.