I'm not seeing any delays, 5 second or otherwise, when using Firefox.

I started noticing how sometimes youtube just seemingly refused to load fully on my phone. I thought it was just my crap internet. But since I use Iceraven, a fork of firefox, it seems that may be why.

I haven't even noticed bc my internet is only 2 Mbps

Not trying to defend Chrome here as I dislike their other behaviours, but just from what's presented in the video, an alternative explanation would be caching. That is, when the reloading is triggered by the switch of user-agent, the cache is reused and thus a shorter load time.

To exclude this effect, the user needs to either

1. Spoof the user-agent and at the same time clear cache (you can disable cache when reloading through the developer's tool), or
2. Clear cache, spoof the user-agent to Chrome. Load page, disable the spoofing, reload.

Does changing the user agent fix this? Anyone tried? I keep forgetting to try it myself.

Reading the comments, It looks to be ad related, and maybe Firefox’s built in privacy tools are the root of the problem?

No wonder why YouTube got weird for me

I feel like Reddit is doing the same shit.

Does not happen for me Safari or Firefox.

What if we are already using YouTube premium and have ublock on FF. Would user agent spoof still be needed??

How annoying.

Once upon a time, Google wanted to kill the user-agent.