I don't think TapFly will work in sport mode but you can do it by manual flight. I does take some practice and I have only done it in P mode. It's pretty cool when it works, not so much when it doesn't.
Oh...by the way, another guy suggested flying it backwards, which is a good idea. Start moving horizontal just above ground level and fly higher while still going horizontal. He said you could reverse the video in post but I haven't figured that out yet!