There is not a great deal of silent-film-related material on Vine, but I think Vine could easily have a substantial 6-second silent film nook. Many portraits of silent film stars are on the web, but a 6-second film close-up can bring a silent performer to life in a way that a portrait cannot. Or in the case of silent comedians, a 6-second gag can show that comedian's style. Vine videos of silent performers could inspire viewers to learn more about him/her.
Some current silent film web sites could serve as Vine gateways, an index of silent performers with links to their Vine videos.
Complete or lengthy versions of copyrighted films (or public domain films with copyrighted soundtracks) should not be pirated and placed on YouTube or similar web video servers. But a 6-second Vine clip should be OK, since it should be "fair use" and could possibly increase the value of the copyrighted work. To be safe, any copyrighted soundtrack could be removed and possibly replaced with public domain music or with freely distributed music from the Internet Archive. (Or the musicians here could donate little 6-second bits for use with silent Vine videos).
Anyhoo...Silent fans with spare time on their hands could (if they learn how) add 6-second silent film clips to Vine. (And should there be one specific "hashtag" linking them?) Here's a sample I uploaded, Anita Stewart:
https://vine.co/v/MuqJ7wm6EXv (click the speaker to turn on the music).
And as a bonus, there are various free apps and web sites which will easily turn any Vine video into an animated gif, like:
