Most downloader sites pull the video onto their server, then hand it to you. This one does not, and that single decision explains everything you notice about using it — including the parts that are slower.
What normally happens
The usual design is a proxy. You give the site a link, its server downloads the video, and then it sends the file to you. Every byte travels twice and the operator pays for both trips.
That is why those sites queue you, throttle you, cap the resolution, or ask for money. Bandwidth is the whole cost of running them, and it scales with every visitor.
What happens here
This server reads two small things: the video page and the stream index, about 330 KB together. It reads back the quality ladder and the signed links, and its job is finished.
Everything after that happens in your browser. It fetches the video segments straight from BoyFriendTV's delivery network and joins them into an MP4 locally. No video byte passes through this server, ever.
Two properties of that CDN make it possible. It sends a permissive cross-origin header, so a browser on another site is allowed to read the segments. And its signed links are not tied to an IP address — a link minted for this server works from your connection. Verified directly: a token issued to a server in Switzerland was used to pull a segment from a connection in Vietnam without complaint.
The catch, stated plainly
BoyFriendTV serves this video as HLS, which means it is cut into four-second pieces rather than sitting there as one file. There is no plain MP4 to hand you — asking the CDN for one returns a refusal.
So your browser has to fetch all 82 or so pieces and stitch them back into a single MP4. That work is real, it happens on your device, and it takes minutes on a large file. The tab has to stay open because the tab is what is doing it.
That is the honest trade. The wait is not a queue and it is not throttling — it is your own connection and your own device doing the job a server would otherwise charge you for.
What you get for it
No queue, because there is nothing to queue for. No cap on quality, so 4K is offered whenever the video has it. No account, because there is no cost to recover. No throttling as more people arrive, because more people cost this server almost nothing.
And a progress bar that counts real segments instead of estimating a percentage, because the browser genuinely knows how many pieces are left.