Digital Marketing expert and writer needed urgently

We have an online tv channel aimed at 60,000 UK marketing professionals that specialises in delivering the latest news and marketing techniques especially in the area of Social Media, SEO and Online Video Marketing. We are look for a digital marketing/online video and social media expert who will write a 500 word news program every week and also regularly add relevant youtube video and articles to our website with announcement tweets. Think it will take about 1-2 hours every weekday.