White flashes between Video Demo slides

In my project there are a lot of white flashes between almost every Video Demo slides (not FMR!). These Video Demos are really short ( just scrolling up or down the screen or drag and drop). How can I solve this problem?

After export my video is squeezed from both sides

Hi! I’ve recorded a software for my E-Learning (software simulation, about 550 slides). In the Captivate preview all slides look great, but in the “HTML5 in browser” preview and after export I have problem with those slides, where I scrolled with the mouse to show something (PDF-Text for example): my video is squeezed from both sides (left and right – see image). Could you please tell me why this happens and what I can do to change it? Thank you!

Publishing for MAC

publishing for MAC