I really enjoyed 12.10 "The VCR illumination", adult Sheldon responds to the message. Everything belongs to Lorre and Prady.
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Texas 1991. "In conclusion, I hope that whenever my future self watches this message that I find these words of some use. Don't give up Sheldon."
11 year old Sheldon stopped the recording and then his bedroom door opened.
"Hello Georgie, can I help you."
"So that's where the video camera is, Dad needs it for the football game tomorrow."
"Fine, I am finished with it for today."
Georgie snatched the camera from Sheldon's hands and left the bedroom.
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Five minutes later Sheldon was sat on his bed reading a Physics book when suddenly a strange noise filled the air and a large blue Police Box emerged in the bedroom. From inside the box Sheldon heard a strangely familiar voice.
"It worked Amy, back to Texas in 1991"
The door opened and a tall, skinny grey haired man emerged with a grey haired lady.
"Look Amy, my old bedroom."
"And there you are, look at that cute little boy."
Sheldon turned to face his young self.
"Thank you for recording the message on the VCR tape. I must say that what I saw recorded on the tape was a great help in our scientific research work. The message eventually helped us make a working time machine..."