Webview scaleToFitPage doesn't scale page to fit in the webView

I am building a simple iOS application in Swift which is built with a webView inside the view. When load a Motion jpeg (mjpeg) in the webView and set

     let reqObj = URLRequest(url: url! as URL)         
     vidView.delegate = self
     vidView.scalesPageToFit = true
     vidView.loadRequest(reqObj)

the pages load as I want in the right scale but after 1-2seconds the web view zooms in without any reason??? It seems to work but goes back and fourth between the scale I want and the zoomed in scale that i down want. I have read that one can set something to the html meta but don't understand how if this is the problem???

This is what I want it to be like but this is what It goes to after a few seconds This is what I don't want it to be like

The web view goes between these 2 content the whole time

Please if someone could help me with this matter and maybe knows what the problem is.