When a video is selected and played over and over again....

[benjames]

I'm working on a video website and have the videos stored in a cloud service, that charges for data transfer.
Please tell me if I'm correct: when a video is selected on a web site to play, the video file is transferred out of the cloud to the website player, and that data transfer has a cost. But when the viewer wants to play it again and select the play button, it isn't transfering from the cloud again is it? It transfer the first time, and is essentially downloaded to the player once, so the extra plays are just looking at the downloaded file over and over right? Not transfering from the cloud over and over, correct?

[newpball]

Typically not.
When a video is streamed it is buffered but generally the buffer is small and not maintained once the video session is over.

[TreeTops]

You know, I would just put the videos on Youtube or Vimeo. Then embed the link code they give you. That would avoid all of the concerns you have about data costs and bandwidth problems.

[benjames]

Once the buffering is over, say on a 60-second video, isn't it now downloaded to the viewers' device? To be re-played without being transferred from the cloud again?

[jagabo]

Once the buffering is over, say on a 60-second video, isn't it now downloaded to the viewers' device? To be re-played without being transferred from the cloud again?

Not necessarily. Security concerns (to prevent people from keeping copies of videos) have largely eliminated that type of full file caching. It will depend on the server and the player.

https://www.adobe.com/devnet/adobe-media-server/articles/digital_media_protection.html