Air in fuel line

Hi all , i have a grand scenic 2011 model , i recently popped the hood to do levels etc and noticed a clear fuel line with loads if air bubbles traveling along it , Car has no issues but was wondering if it is normal .



It's a 1.5 dci engine . I have posted a link to a video i made of it .



Many thanks



Graham



http://ift.tt/1vNRQ0O