  Compliance with public health measures, such as restrictions on movement and
socialization, is paramount in limiting the spread of diseases such as the
severe acute respiratory syndrome coronavirus 2 (also referred to as COVID-19).
Although large population datasets, such as phone-based mobility data, may
provide some glimpse into such compliance, it is often proprietary, and may not
be available for all locales. In this work, we examine the usefulness of video
sharing on social media as a proxy of the amount of time Internet users spend
at home. In particular, we focus on the number of people sharing YouTube videos
on Twitter before and during COVID-19 lockdown measures were imposed by 109
countries. We find that the media sharing behavior differs widely between
countries, in some having immediate response to the lockdown decrees - mostly
by increasing the sharing volume dramatically - while in others having a
substantial lag. We confirm that these insights correlate strongly with
mobility, as measured using phone data. Finally, we illustrate that both media
sharing and mobility behaviors change more drastically around mandated
lockdowns, and less so around more lax recommendations. We make the media
sharing volume data available to the research community for continued
monitoring of behavior change around public health measures.
