Crew member visa is for pilots and crew members of foreign airlines to fly into the US, for example an Air Canada flight operating into the US. The US is different in the respect that they require a crew visa for all foreign crews, including those from countries that belong to the Visa Waiver Program. Their take on it is that you are "working" within the borders of the US, therefore you require a visa.
What a previous poster was referring to with respect to Canadians not eligible and Sri Lankans eligible is the Diversity Lottery. The rules for the DV-2015 state
For DV-2015, natives of the following countries are not eligible to apply, because more than 50,000 natives of these countries immigrated to the United States in the previous five years:
Bangladesh, Brazil, Canada, China (mainland-born), Colombia, Dominican Republic, Ecuador, El Salvador, Haiti, India, Jamaica, Mexico, Nigeria, Pakistan, Peru, Philippines, South Korea, United Kingdom (except Northern Ireland) and its dependent territories, and Vietnam