I sent my CV and cover letter to AlphaSights London, I received a video interview request a day later and was given 4 days to submit my video. I prepared for it quite well (I gathered all the questions read on Glassdoor, prepared the answers and practiced filming myself), and submitted the video interview three days later. I did not receive a response from AlphaSights, sent a follow-up email about 10 days later, but did still not receive an answer. I've heard some negative feedback about their recruitment system, although they seem like an awesome team to work for!