I don't have the time to watch the entire video, sorry, but it seems like you scale the model globally: you have to scale every polygon along it's normal, the shortcut is 'alt+s'.

to flip the normals, simply press 'w' and click "flip normals".

at least these are the shortcuts for the blender version I use.
for both, the scaling and flipping the normals, you have to select the whole model.

Edit: well, looks like the video isn't as long as I expected... from what I saw you did everything right, there's just a scale problem when converting the model.
maybe you could try another format like fbx.