what video format is popular today

[DanielGrola]

Using MP4 for what it's worth

[Sneaky]

Anything change in the past 5 years?

[tacnet]

WebM is now pretty much supported across the board (95.81%) https://caniuse.com/webm

Only IE doesnt support it but nobody really worries about that. (IE stopped development in 2013 and doesnt support any of the latest file formats)

[fetishnews]

WebM my preferred choice.

[jag]

I would go with WebM as it is the latest format assuming your script supports it not all older scripts can handle it,they need to be updated.

[misterporn]

Whatever Google likes is the flavour of the day

[Luke]

Whatever Google likes is the flavour of the day

Sadly true we are slaves to Google.