Which Linode plan would be best for video streaming?
If it would be helpful we do have a guide on setting up a Plex Media Server which would allow you to stream video from anywhere. The Plex guide specifically mentions to use a Dedicated CPU instance as well.
As for the specific size plan, that really depends on the quality, size and type of the video files you'd be hosting, as well as the type of storage (such as whether the data is stored on your Linode or remotely). This Community post goes into this a little more, though it's specifically in reference to GPU servers.
My suggestion would be to start with a Nanode or 2GB Dedicated plan, then resize your server larger as needed. Note: this would require some downtime during the resize, which is something to consider if this will be a production server used by your customer base. If that's the case I'd recommend some sort of high availability setup or utilization of a NodeBalancer.
Another factor to consider is how far you or your customers are from where the videos are being hosted. I'd recommend running a few speed tests to help you determine which data center would be the best fit for your needs. Here is a link to our speed test page if needed.
Lastly, you may find this article on video streaming optimization helpful.