She thought it might spread some holiday cheer, but little did she know just how well.
"We are all very touched by the incredible response," she wrote, "and I'm glad by posting the video I've been able to spread the love, especially at this time of year."
The 24-year-old, who lives in a seaside town in Scotland, visits her grandfather, 87-year-old Robert, about once a week.
"On a normal visit, we have a cup of tea and a catch up," she told GMA Digital reporter Nicole Pelletiere. "I just filmed him because I loved his reaction to seeing me."
Barclay put together a compilation of several of his joyful greetings, and now it has millions of views on Twitter. Reactions to the video ranged from compliments on Robert's sweater to reflections on the importance of grandparents.
Grandparents are such angels. Please cherish yours with all your heart. 💙😭 https://t.co/nmjx2XSIzu— Hannah Gibbons X (@hannahgibbo92) December 15, 2018
hes so freaking cute with his sweaters on omg https://t.co/HEtxLwLCU8— rhi (@rhinextdoor) December 15, 2018
What I would do for one more visit with my own. This just made my heart so full 💛💛 https://t.co/Q7HY3t85PF— Ellie Roberts (@elizabethmayx0) December 15, 2018
The compilation got so much love that the social media site created a Twitter Moment about it. Barclay wanted to keep spreading the love, so she created an Instagram account to share more moments with Robert.
It's clear from her posts that Barclay does not take her sweet grandfather for granted.
"He's my no.1 guy," she wrote on Twitter. "I love him with all my heart."