Add Japanese translate for #4911 (#4943)

app/javascript/mastodon/locales/ja.json

@@ -195,15 +195,15 @@
   "upload_button.label": "メディアを追加",
   "upload_form.undo": "やり直す",
   "upload_progress.label": "アップロード中...",
-  "video.close": "Close video",
-  "video.exit_fullscreen": "Exit full screen",
-  "video.expand": "Expand video",
-  "video.fullscreen": "Full screen",
-  "video.hide": "Hide video",
-  "video.mute": "Mute sound",
-  "video.pause": "Pause",
-  "video.play": "Play",
-  "video.unmute": "Unmute sound",
+  "video.close": "動画を閉じる",
+  "video.exit_fullscreen": "全画面を終了する",
+  "video.expand": "動画を拡大する",
+  "video.fullscreen": "全画面",
+  "video.hide": "動画を閉じる",
+  "video.mute": "ミュート",
+  "video.pause": "一時停止",
+  "video.play": "再生",
+  "video.unmute": "ミュートを解除する",
   "video_player.expand": "動画の詳細",
   "video_player.toggle_sound": "音の切り替え",
   "video_player.toggle_visible": "表示切り替え",