This will be set to unlisted when Jayce is released (Abilities at the bottom).
We posted the direct links to the Riot Cloudfront and then people started to ask for youtube mirror so here it is.
Q - To the Skies / Shock Blast
W - Static Field / Hyper Charge
E - Thundering Blow / Acceleration Gate
R - Deformation: Mercury (?) Hammer/Cannon Skill names based on sound files. "Unconfirmed way of transforming weapon"
Reddit post regarding Jayce's skills: