remove slow motion playback

Hello,

I need some help with playback of a video clip someone gave me. It starts out at normal speed then about 5s in goes into slow motion for the rest of the video, total playback about a minute. I have a iPhone 5S, an iMac, a macbook air & a windows 10 machine... I really don't care what device I use I just want to kill the slow motion and save it to play at normal speed.

The person that recorded the video did it on an iPhone and the slow motion was intentional. Is there an easy way to change it?

Note: I downloaded slow-fast on my iPhone and was able to get it to play normal speed with some messing around but can't (or don't know how) to save it... Again, I don't care what platform or software I have to use to do this, just prefer not to have to purchase something.

Thanks for your help.

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