Have you tried it recently? They changed to a new captcha not so long ago, after which the transaction accelerator was available most of the hour. It used to tell me I beat 95% of the users with the captcha. Now, it tells me I beat 8% of the captcha, and the accelerator is instantly unavailable. So I can only conclude bots fill it up, and it could even be someone created a paid service that relies on ViaBTC.