On desktop you can use the share button but on mobile you don’t get the option. Fortunately you can add a code to the link to let YouTube know where to start from. Just add ?t=00h00m00s to the end of the link where h = hours, m = minutes and s = seconds.
Here is some sage investment advice from Ray Dalio at the 27 second mark
And Warren Buffet’s response at 4 minutes 17 seconds
Please note that Facebook Messenger and some other apps give a thumbnail preview. The recipient needs to click the actual link. If they click the image it starts from the beginning.