In the UK, our Prime Minister is stepping down and there are a number of Conservative Party MP's who are campaigning for his job. Some of them have released publicity campaign videos. I have noted that one of the candidates (Penny Mordaunt) has used a clip of mine that was bought through Shutterstock. The video can be seen here: https://www.pm4pm.com/. My video clip is designated for editorial use only. Is a political campaign video of this nature regarded as editorial?

Not quite sure where I would place a campaign video between commercial and editorial - bit in the middle in my opinion. However, be aware that in the terms Shutterstock can license an editorial image for commercial use "at their discretion". I think that's been the case for several years now.
Take a look at any editorial image on the buyers site. There's a note saying to get in touch if you want to use an image/clip for commercial purposes. Subject to agreement they offer Asset Assurance which indemnifies the buyer against any claims.