This is an incredibly serious action.

express an opinion or belief that is supportive of a proscribed organisation, reckless as to whether a person to whom the expression is directed will be encouraged to support a proscribed organisation

You literally cannot say anything that could even be construed as support for the organisation. This incredibly mild video, were it uploaded after the proscription instead of shortly before it, would be potentially illegal, even though it is primarily focused on criticising the government for its authoritarian overreach.

It’s the first time this has been done to an organisation that isn’t even causing bodily harm. The only thing they’ve ever damaged has been property. It’s an extreme McCarthyesque overreach. Do not think of this as “just more of the typical UK government support for Israel’s genocide”. It’s a huge escalation of that support and an abuse of power.