Question: What group did Marketa Irglova's "Once" co-star perform in?

Context paragraphs:
Social compensation: Social compensation is considered the complement of social loafing, and refers to when individuals work harder and expend more effort in a group setting - to compensate for other group members - compared to when working alone.  Social compensation is consistent with the expectancy-value formulations of effort theory.  Williams and Karau first documented the social compensation hypothesis.  The social compensation hypothesis states that there are two factors under which social compensation may occur: the expectation that other group members will perform insufficiently and if the group product is important to the individual.  More specifically, the hypothesis states that if a group member is perceived to perform insufficiently either due to trust, reliability, or direct knowledge, or if an individual perceives a task or product as personally meaningful, then an individual may contribute more towards the collective product in order to avoid an inadequate performance.  Social loafing is considered the complement of social compensation.

Sean Forbes: Sean Forbes (born February 5, 1982 in Detroit) is a deaf American hip-hop artist.  Sean became deaf from spinal meningitis when he was just a few months old.  The cause was never officially diagnosed but Sean has said that they (the doctors) had suspected spinal meningitis.  Sean's parents bought him a drum set when he was 5 years old and he started writing songs and playing guitar when he was 10.  Sean grew up playing music with his siblings.  His dad, Scott Forbes, is in a Detroit country-rock band called The Forbes Brothers.  Sean's mom is a pianist.  "They played everything from The Rolling stones to The Beatles, all big band music and stuff like that."  Sean attended R.I.T./N.T.I.D. where he graduated with a bachelor's degree in multi-disciplinary studies focusing on management, accounting, and communications.  Eminem was one of the first people to actually see one of Forbes' music videos.  Sean's long-time producer and collaborator is Jake Bass, and together they have penned over 100 songs, many of which they perform live.  Sean recently had Oscar award-winning actress Marlee Matlin co-star in his music video for the song "Let's Mambo."  "Rapping is just something that I do because you don't want to hear me sing."

Musical ensemble: A musical ensemble, also known as a music group or musical group, is a group of people who perform instrumental or vocal music, with the ensemble typically known by a distinct name.  Some music ensembles consist solely of instruments, such as the jazz quartet or the orchestra.  Some music ensembles consist solely of singers, such as choirs and doo wop groups.  In both popular music and classical music, there are ensembles in which both instrumentalists and singers perform, such as the rock band or the Baroque chamber group for basso continuo (harpsichord and cello) and one or more singers.  In classical music, trios or quartets either blend the sounds of musical instrument families (such as piano, strings, and wind instruments) or group together instruments from the same instrument family, such as string ensembles (e.g., string quartet) or wind ensembles (e.g., wind quintet).  Some ensembles blend the sounds of a variety of instrument families, such as the orchestra, which uses a string section, brass instruments, woodwinds and percussion instruments, or the concert band, which uses brass, woodwinds and percussion.

Midi lidi: Midi lidi is Czech underground electro band, which is particularly notable for its unusual Czech lyrics of their songs for its genre.  The group consists of Peter Mark, Prokop Holoubek, Marketa Lisa, Tomino Kelar and more.  Group created music for Marek Najbrt's films "Protector" and Polski film and recently also for documentary film "Czech Peace".

Once (film): Once is a 2007 Irish romantic musical film written and directed by John Carney.  The film stars Glen Hansard and Markéta Irglová as two struggling musicians in Dublin, Ireland.  Hansard and Irglová had previously performed music as the Swell Season, and composed and performed the film's original songs.

List of The Generation Gap episodes: This is a list of episodes for the 1969 game show "The Generation Gap".  Each week, musical guests would appear and perform, while various celebrities appeared as both "special guests" and contestants.  These included "Looney Tunes" voice actor Mel Blanc, "Dark Shadows" co-star David Henesy, and future "To Tell the Truth" host Garry Moore.

Joe Doyle (musician): Joe Doyle (born May 8, 1977) is the bassist and backing singer for Irish rock band The Frames and The Swell Season.  He has been a member of The Frames since 1996, appearing on six albums to date.  In addition to appearing on Frames albums, he has also plays bass and contributes backing vocals to two Swell Season albums: the soundtrack to "Once" and "Strict Joy."  He is currently touring as a member of the Swell Season, which also includes Glen Hansard (vocals/guitar), Marketa Irglova (vocals/piano), Graham Hopkins (drums/backing vocals), Rob Botchnik (lead guitar/backing vocals) and Colm Mac Con Iomaire (violin/backing vocals).  Doyle originates from Allenwood, County Kildare, Ireland.

Ghantapatua: Ghantapatuas (Also Patua) (Oriya: "ଘଣ୍ଟପାଟୁଆ", a performer beating "Ghanta") are traditional male folk artistes from the Indian state of Odisha.  They work as temple servants in the goddesses' temples and perform in Jhama nata during Pana Sankranti, celebrated mainly in Odisha.  On the day of Pana Sankranti, performers ("Patua") dressed in traditional Odishan dress walk holding.  Males of castes "bauri", "dama", "kandara" and "pana" perform as Ghantapatua.  In some of the places in Odisha, ghantapatuas pierce metal nails and tie rope with them to hooks and perform.  They offer the dance to goddesses Sarala, Hingula, Charchika, Bhagabati, Mangala and Chandi as servants.  Ghantapatuas perform in a group of two or four perform wearing dresses that resemble women's dresses.

Johnny Boyle: He then joined The Frames initially as a session drummer, but joined the band full-time soon after.  He has also played on the Once tour with Glen Hansard and Marketa Irglova.

Glen Hansard: Glen Hansard (born 21 April 1970) is an Irish songwriter, actor, vocalist and guitarist for Irish group The Frames, and one half of folk rock duo The Swell Season.  He is also known for his acting, having appeared in the BAFTA-winning film "The Commitments", as well as starring in the film "Once", which earned him a number of major awards, including an Academy Award for Best Song.

Supporting paragraphs: Glen Hansard Once (film)
Answer: The Frames