url preview ruins the rickrolls by unfurling. rickrolling is considered as one of the pillars of the online chat culture and should be taken seriously.
this particular video should not be unfurled:
it’ll be great to have a pattern matching exclusion for link previews in administration, so each culture can decide on the particular song.
I believe there is a message property to stop previews… so a Rocket.Chat app or posting via api this should be possible
what about something like
/spoiler https://www.youtube.com/watch?v=dQw4w9WgXcQ
This can easily be implemented with Rocket.Chat Apps-Engine 
That would be a fantastic first app!
Looks like would just need to set the parseUrls to false on the message object: https://github.com/RocketChat/Rocket.Chat.Apps-engine/blob/master/src/definition/messages/IMessage.ts#L21
Also if you want something like the forum spoiler… could put in attachment and use the collapsed property to send it collapsed:
https://github.com/RocketChat/Rocket.Chat.Apps-engine/blob/master/src/definition/messages/IMessageAttachment.ts#L12
Is this possible with the REST client? Only Apps Engine?
Sending parseUrls as false in the REST API doesn’t appear to have the desired effect.