what scaler is this?

[bxyhxyh]

https://www.youtube.com/watch?v=4EBPRgS_2XQ

His recent uploads look like this.
And I think this upscale looks nice.

What kind of scaler do you think it is?

nnedi doesn't look like this. Maybe waifu?

[Bloax]

Looks like plain bilinear to me?

[bxyhxyh]

Then please look at this https://www.youtube.com/watch?v=k42vvbRnXAY

[TheFluff]

I can't tell the difference between all the pixel art scalers but it's probably just hqx or SaI or something. You can try them in Avisynth with this plugin: http://forum.doom9.org/showthread.php?t=154674

[Bloax]

Judging by the softness of the first video I'd still say it's either straight bilinear or plain 2xSaI.

This other video you posted seems to be using something entirely different, which looks more like hqNx.

[bxyhxyh]

First video, there is not heavy aliases, so I thought it might something different than standard resizers of avisynth.
It might be related to compression or something though.