It just takes few seconds to make the changes and if you aren't impressed by it, then you can easily disable the changes nonetheless.
So, open the Nautilus and from the menu choose, "Edit" -> "Preference" -> "Preview". Now you should get a window similar to the below.
1. Show thumbnails - As you can see, the default option is "Local files Only". By clicking on that button you'll get a menu from that choose "Never".
Beware that by doing so, you're disabling Nautilus creating thumbnail previews of video and images while browsing.
Or, if you want your images to show as thumbnails but want the video thumbnails to be disabled, then keep the "Local files Only", option and click on the "Only for files smaller than" and choose a low value (500KB or 1MB for instance, do some testing...).
Since videos usually come with bigger values/sizes, this should disable creating those previews but unless you have some high quality images with bigger in sizes, most of your images should be showed as thumbnails.
2. Preview sound files - If you don't want Nautilus to automatically generate previews of audio files when your mouse go over them, then as before, click on the button and choose "Never".
This mainly helps to prevent calling for the Nautilus addons every time you go over the files which requires both CPU and RAM mainly (should speed up under "heavy" audio file collection folders sometimes).
3. Count number of items - Although you can disable this, still Nautilus counts the items... So... at the moment, you can't disable it (would have been handy). :)