Hi OP, I'm a detective who regularly conducts video interviews (VRIs) so hopefully I can give a bit of advice 😊
VRIs are conducted with vulnerable and intimidated witnesses and basically an appointment will be made for you to attend a VRI suite where you will meet with two investigators. You'll have a chat beforehand as part of the "assessment" we're they will basically just assess your free recall etc (in case you need any help from an intermediary) and they'll probably show you around the suite.
There will be a room that typically has two cameras in - one that points directly towards where you will be sat and then one that covers the whole room in order to show who is in there. There will be a second room where the second investigator will sit - they will monitor the recording and take notes on behalf of the investigator who is interviewing you so that they can focus on what you're saying.
Once the recording starts, the lead investigator will go through introductions and the basically say "were here because of x, y and z so when you're ready, talk me through it" and then you basically just tell them what's happened. They'll know beforehand exactly what needs to be covered for the "points to prove" so they will let you talk about it all on your own words (and shouldn't interrupt unless you're veering massively off topic) and then they'll likely ask question after just to get you to elaborate on some stuff and to make sure that all of the elements of the offence have been covered.
They'll likely also ask about the impact the offence has had on you - don't worry about getting emotional etc - VRIs are fantastic for truly showing how something has effected you, as opposed to a written statement which can be quite monotone.
You won't be allowed to have anyone in there with you but you can take someone along for support - they will wait for you in a waiting room and if you need to take a break for any reason (whether it's a toilet break or it gets a bit too much) they will happily pause the recording and let you do that.
Like the other poster said, it's also a way to help you with the court process - you will probably still have to go to court if it's a not guilty plea but your main evidence will be the recording which can just be played as opposed to a written statement which you would have to stand up and read to the court. Being a vulnerable or intimidated witness means you're eligible for special measures too - so measures can be put in place at court to prevent you seeing the defendant such as a screen in place or giving evidence from another room over livelink (live video).
If you have any questions feel free to ask :)