There is no requirement to do this, however it is of course, very sensible. Like things like PAT testing - people assume it's a requirement. The employer would, of course be responsible if there was a fire and people did not know what to do.
Why we have to turn to on-line training for every little thing is beyond me!
The best training for your staff comes from you. YOU know what they need to know. I had experience of a trainer delivering a fire safety course to staff after a near miss! At the end, I (as a contractor present) quietly told him they'd all got horribly confused. He assumed they had plans, and the system in place would work. There was no plan, and the systems relied on individuals who worked part-time and would not always be there. He was horrified and realised the manager who arranged the course had no idea, so assumed he would do everything = he thought he was there to show them fire extinguishers, explain procedures and how to do evacuations etc. The plan, was simply that if the fire alarm went off, everyone would leave the building quickly and collect across the rd. Nobody had thought that somebody with the signing in sheets would be key to finding out if everyone was there. The alarm has a silent checking mode to give the chance to cancel it before it goes ogg publicly to save false alarms. The manager didn't realise this was why it made a funny noise for 3 minutes. The fire brigade, faced with repeated and numerous false alarms set off my idiots in a bar, downgraded priority unless they received a phone call, rather than the audio alarm. Fire hoses had been disconnected by the fire service two years previously and nobody told the staff they didn't work. When pointed out, half the people would have tried to use them. Frequent small real fires often get caused by cigarettes thrown away outside on wooden decking type surfaces, yet the staff often try to put them out with CO2 extinguishers, outside, in the wind.
Somebody needs to do real risk assessments and then design PROPER training specific to the risks identified. The law goes into action after the incident. Training helps prevent it actually happening. Watching an internet presentation provided a tick in the box - yes, they have been trained, but if the training is crap - their lives are still on the management's shoulders, and in most incidents, it really falls onto the shoulders of one or two. Remember Hillsbrough? If there is a risk and they need fire training, then the person who carries the can should really do it. If that person cannot do it, then why are they responsible for it? If you delegate, and that person messes it up, you will still be standing in front of the judge.
You don't HAVE to do it, there is no law stating "thou must do fire training", but you have that duty of care - you need to keep them safe.
I've had to evacuate over 1400 people from a theatre with my own people because the venue staff had been trained to run like hell when the alarm goes off - leaving the audience to fend for themselves. The venue did not understand that the audience were actually their responsibility - their training only covered the staff. The realisation afterwards was sobering for them. They genuinely did not know. I spent many years teaching modules in managing safety, and finding out in real life these things are just not known about scares me. A generic internet video is NOT training, it's just base level knowledge. The training then follows.