Recruiters want to be confident in their candidates commitment to making a career change. In other words, if you choose to work with a headhunter, you d better have a mindset demonstrated by your response, attitude and urgency. Otherwise don't get involved in the interviewing process with a headhunter unless you mean it. Candidates need to do their research and demonstrate that they're businesspeople. They have to understand the challenges and opportunities that any given employer is facing.
Information is available online even on companies that don t have their own web sites.
Chances are, there have been articles written about those companies or their products. At minimum, get company brochures from your recruiter. Recruiters want you to win in the interview, so it will help them to help you with research. First interviews are either by phone or through videoconferencing. Standing up to remain alert while taking a phone interview is one of the tips that recruiters gives their candidates.