The winning entries will be screened at a gala event in London next month, and will also be shown on the Community Channel and at special regional screenings.
The competition is being run in conjunction with the Year of the Volunteer, and all entries will be archived for future use by the media.
Damian Radcliffe, national broadcast manager at CSV, says: "The standard of entries has been really good so far; there have been some incredibly moving stories.
"We hope that by seeing others get something out of volunteering, people will be inspired to volunteer themselves.
"But it's not just about getting new people to try volunteering; it's also about giving people the chance to tell their own stories. There's no editorial agenda so it means people will get to hear voices that normally go unheard."
Helen Potter began volunteering at the Burd drop-in centre for people with mental health issues in Gwent, Wales, after she was diagnosed as a manic depressive. She has made a digital story, comprising a collection of stills with a voiceover, for Volunteer Britain. She says: "Volunteering helped my confidence and self-esteem, so much so that I went back to education to get a BTec in counselling.
"I felt people responded to me because they knew I could relate to what they were going through. They also knew I was there because I wanted to be, not because I was getting paid.
"I decided to make a digital story because I wanted to show people that, even if you are diagnosed as a manic depressive or have other mental health issues, you can rebuild your life."
Potter adds: "A lot of people who might think they have nothing to offer as a volunteer have experiences of, say, dealing with a particular illness, which would help them relate to others in a similar position."
The Volunteer Britain competition closes on 16 September. Visit www.csv.org.uk/volunteerbritain.