Jj, the bowel screening camera didn’t go as far round the bowel as a colonoscopy camera does, and didnt require the same bowel prep stuff as the whole bowel didn’t need to be emptied.
For a colonoscopy, a low residue diet has to be followed for a few days prior to the procedure, and litres of some special stuff has to be drunk for 24 hours preceding the procedure, which makes for lots of watery bowel movements to ensure the entire bowel, right the way round, is completely empty.