I just checked some old Winston files my toddler daughter wrote back then. (Great fun btw, but sadly only attracts attention with sound on.) Her pattern is higly repetitive, and you a have a quite high share of fghj (also seen in the video with Max) in there. Single shifted chars? Quite unlikely.

http://www.rengelbert.com/winston/

  ydwew346rr764847uruejdjeyytr4t5t5ty8uoff                    jfgjjhv rr rgr r rrrrh jjjhhhju5m    
 ytj8ikm ,k88o0pfffuyhfjdjuddjcie8kdduuukjfuruuryfuuugtt767yut67y7hcfght    h7tyty5y6 uyhtryty gyfg 
 huy tyhrty7 ruy6t5y5777h hyuyu utygj tgytu jtgtu 5ugjuy 5676uvu 2355 hfhghhhhhu7uuuytutut juyy 
 umnhjbbvvgyy6tg7777.
 bdy7er64y5y574757r04iiiiiutweepiroeiwijwdryyt h7f77fuuvyf77f7uuyutuhturghghyhyggyvbg fyr        
 gfrt6rfytyftr6 tryy        hyyyy675g ttyty57 htgtt6t667 t65r7745 
 y6767nghnggugg7uuupooooooiuuuuytrewq    kkha bcx 
 gtytttmhguyuuhuuuygyufh7673y7rtty7yggffrtdyteryurijrf 
 uu4hfyuytttgt7t7yrfyrtuyu