Fix broken video embed

## Issue
Closes 5811: Video-embed in markdown-post is broken

- Revert "Fix 'makeSelectIsPlaying' to look at 'playing' instead of 'primary'." dabdc980a1.
- Revert "Fix 'isPlaying' to reflect 'playing' instead of 'primary' URI" 351890decf.

Reverting means "Deleting MD from downloads list causes spinning icon to run forever 4959" gets re-opened, but this is a way less severe issue to leave in.

ui/component/fileRenderInline/index.js

@@ -1,14 +1,14 @@
 import { connect } from 'react-redux';
 import { makeSelectFileInfoForUri, makeSelectStreamingUrlForUri } from 'lbry-redux';
 import { doClaimEligiblePurchaseRewards } from 'redux/actions/rewards';
-import { makeSelectFileRenderModeForUri, makeSelectIsPlaying } from 'redux/selectors/content';
+import { makeSelectFileRenderModeForUri, selectPrimaryUri } from 'redux/selectors/content';
 import { withRouter } from 'react-router';
 import { doAnalyticsView } from 'redux/actions/app';
 import FileRenderInline from './view';
 
 const select = (state, props) => ({
   fileInfo: makeSelectFileInfoForUri(props.uri)(state),
-  isPlaying: makeSelectIsPlaying(props.uri)(state),
+  isPlaying: selectPrimaryUri(state) === props.uri,
   streamingUrl: makeSelectStreamingUrlForUri(props.uri)(state),
   renderMode: makeSelectFileRenderModeForUri(props.uri)(state),
 });

ui/redux/selectors/content.js

@@ -29,7 +29,7 @@ export const selectPlayingUri = createSelector(selectState, (state) => state.pla
 export const selectPrimaryUri = createSelector(selectState, (state) => state.primaryUri);
 
 export const makeSelectIsPlaying = (uri: string) =>
-  createSelector(selectPlayingUri, (playingUri) => playingUri && playingUri.uri === uri);
+  createSelector(selectPrimaryUri, (primaryUri) => primaryUri === uri);
 
 export const makeSelectIsPlayerFloating = (location: UrlLocation) =>
   createSelector(selectPrimaryUri, selectPlayingUri, selectClaimsByUri, (primaryUri, playingUri, claimsByUri) => {