Tearing down a HTMLMediaElement renderer may cause it to start playing: WebCore 0x0000000192132ec4 WebCore::HTMLMediaElement::enterFullscreen(unsigned int) + 176 (HTMLMediaElement.cpp:5901) 4 WebCore 0x0000000192120a5c WebCore::HTMLMediaElement::updatePlayState(WebCore::HTMLMediaElement::UpdateState) + 264 (HTMLMediaElement.cpp:5306) 5 WebCore 0x000000019212b618 WebCore::HTMLMediaElement::playInternal() + 972 (HTMLMediaElement.cpp:3551) 6 WebCore 0x000000019212b6cc WebCore::HTMLMediaElement::play() + 176 (HTMLMediaElement.cpp:3479) 7 WebCore 0x0000000192136a04 non-virtual thunk to WebCore::HTMLMediaElement::resumeAutoplaying() + 204 (HTMLMediaElement.cpp:7472) 8 WebCore 0x00000001924880f8 WebCore::PlatformMediaSession::endInterruption(WebCore::PlatformMediaSession::EndInterruptionFlags) + 512 (PlatformMediaSession.cpp:166) 9 WebCore 0x000000019280c320 WebCore::RenderTreeUpdater::tearDownRenderers(WebCore::Element&, WebCore::RenderTreeUpdater::TeardownType, WebCore::RenderTreeBuilder&)::$_5::operator()(unsigned int) const + 48 (RenderTreeUpdater.cpp:583) 10 WebCore 0x000000019280b46c WebCore::RenderTreeUpdater::tearDownRenderers(WebCore::Element&, WebCore::RenderTreeUpdater::TeardownType, WebCore::RenderTreeBuilder&) + 572 (RenderTreeUpdater.cpp:591) 11 WebCore 0x000000019280aca4 WebCore::RenderTreeUpdater::updateElementRenderer(WebCore::Element&, WebCore::Style::ElementUpdate const&) + 408 (RenderTreeUpdater.cpp:321) 12 WebCore 0x000000019280a290 WebCore::RenderTreeUpdater::updateRenderTree(WebCore::ContainerNode&) + 1188 (RenderTreeUpdater.cpp:200) 13 WebCore 0x0000000192809d58 WebCore::RenderTreeUpdater::commit(std::__1::unique_ptr<WebCore::Style::Update const, std::__1::default_delete<WebCore::Style::Update const> >) + 592 (RenderTreeUpdater.cpp:132) 14 WebCore 0x0000000191f353c0 WebCore::Document::resolveStyle(WebCore::Document::ResolveStyleType) + 1036 (Document.cpp:1864) 15 WebCore 0x0000000191f35d7c WebCore::Document::updateStyleIfNeeded() + 344 (Document.cpp:1968) 16 WebCore 0x0000000191de910c WebCore::updateStyleIfNeededForProperty(WebCore::Element&, WebCore::CSSPropertyID) + 108 (CSSComputedStyleDeclaration.cpp:2470) 17 WebCore 0x0000000191de8598 WebCore::ComputedStyleExtractor::propertyValue(WebCore::CSSPropertyID, WebCore::EUpdateLayout) + 144 (CSSComputedStyleDeclaration.cpp:2681) 18 WebCore 0x0000000191de7f7c WebCore::CSSComputedStyleDeclaration::getPropertyValue(WebCore::CSSPropertyID) const + 76 (CSSComputedStyleDeclaration.cpp:2419) 19 WebCore 0x0000000191494144 WebCore::jsCSSStyleDeclarationPrototypeFunctionGetPropertyValue(JSC::ExecState*) + 316 (JSCSSStyleDeclaration.cpp:431) Seems to be a result of this code: void HTMLMediaElement::didDetachRenderers() { updateShouldAutoplay(); }