To check the watchtime in hours simply divide the minutes by 60. I.e. if you have 6000 minutes of watch time, that's 100 hours of watch time. And btw if your stats are huge, YouTube analytics give you the results in hours (even years) for better overview.
Back in 2015 in order to be able to contact YouTube staff with direct e-mail support they required the channel to have 15,000 watchtime hours for the previous 90 days! While it sounded pretty impossible to achieve for the small YouTubers like I was back then, by a happy coincidence they just introduced Live Streaming. So I've streamed a pretty popular game and my stream was getting 40-50 concurrent viewers at time. Thanks to the stream (also the watchtime from the regular videos and the archived streams), I was able to achieve the goal and finally contacted a human at YouTube and asked for a feature to be enabled to me (which they did).