I went to take a photo on my digital camera but I didn't realise I had the record setting on, so I have now got a 1 second video Is there a way that I can turn the initial frame of the video into a photo? - i.e. get it developed as a photo.

My digital stills camera also records the first frame of video as a low q JPG when taking video, for indexing.

Download it and see what you get.

Otherwise, screen grab or
"save frame as" in some apps.

I believe VLC allow frame grabs. I will warn you quality probably won't be very good.