YouTube recently announced a decision to exclude potentially harmful content from video recommendations while allowing such videos to remain on the platform , but it is unclear whether this compromise is sufficient in mitigating YouTube's role in propagating this content . To assess this impact, we measure YouTube sharing in Twitter and Reddit  in the eight months around YouTube's announcement using interrupted time series models. These models evaluate YouTube's impact on sharing of videos from a curated set of alternative political channelsand popular videos shared in three conspiracy-oriented Reddit subreddits; we compare these models to a placebo dataset of makeup-oriented videos that should be unaffected by YouTube's announcement. Results suggest YouTube's de-recommending AIN-produced content has a significant suppressive effect on sharing of AIN videos in both Twitter and Reddit , with our models showing a significant and downward trend in sharing. For conspiracy video sharing , however, we see no significant change in Reddit and find an increase in the level of conspiracy sharing in Twitter. We see no significant effect on makeup sharingin either platform , suggesting YouTube's targeting particular content types has a targeted effect. Reducing exposure to anti-social videos without deleting them therefore has the potential to improve quality across the information ecosystem, but additional transparency is needed to evaluate these effects further.
In January 2019, YouTube announced it would exclude potentially harmful content from video recommendations but allow such videos to remain on the platform . While this step intends to reduce YouTube's role in propagating such content, continued availability of these videos in other online spaces makes it unclear whether this compromise actually reduces their spread . To assess this impact, we apply interrupted time series models to measure whether different types of YouTube sharing in Twitter and Reddit changed significantly in the eight months around YouTube's announcement . We evaluate video sharing across three curated sets of potentially harmful, anti-social content: a set of conspiracy videos that have been shown to experience reduced recommendations in YouTube, a larger set of videos posted by conspiracy-oriented channels, and a set of videos posted by alternative influence network (AIN) channels. As a control, we also evaluate effects on video sharing in a dataset of videos from mainstream news channels. Results show conspiracy-labeled and AIN videos that have evidence of YouTube's de-recommendation experience a significant decreasing trend in sharing on both Twitter and Reddit . For videos from conspiracy-oriented channels , however, we see no significant effect in Twitter but find a significant increase in the level of conspiracy-channel sharing in Reddit. For mainstream news sharing, we actually see an increase in trend on both platforms , suggesting YouTube's suppressing particular content types has a targeted effect. This work finds evidence that reducing exposure to anti-social videos within YouTube, without deletion, has potential pro-social, cross-platform effects. At the same time, increases in the level of conspiracy-channel sharing raise concerns about content producers' responses to these changes, and platform transparency is needed to evaluate these effects further.
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