If you can provide a little more info it may help if tracking down what may be causing your issue.
What is the format of the video?
Does the video play normally in the connect drive app?
What is the iOS version of the iphone you are using?
What type of wifi router are the iOS device connect and chromecast connected to? Make and model?
How far away from the router is the connect drive when you are trying to fling to chromecast?
