Imagine that there is a video site like youtube, it uses personalized content for users based on their Geo, referring site data, cookies and similar. On certain pages different users might see different set of videos offered to them.

Users who came from Japan will see video selection that is more engaging for Japanese users, so they would watch more videos, UK users will see different videos offered.

Also, users who were referred from site A will have another selection of videos, and users, who came from Google SERPs will see video selection personalized as well - hotter, trending, popular videos. Logged in users (with cookies) would see different video selection. 

It's not that the site would show something different to Googlebot, but page templates will stay more or less the same, but just videos (thumbs, titles, links) get personalized to maximize user engagement, and even if user is returning to the site in an hour, he might see different videos offered than what he saw last time.

Actually, it's the way Youtube works. Everyone sees some different sets of videos offered, trends, recommendations, "popular in your country" - personalized content.

Will Google see that as cloaking?

What should we do to stay on the safe side?