Harald OK, Let's do a quick update:
I replace youtube link with this, but I am not sure if it's a proper code for embed iframe video player:
<iframe width="560" height="315" src="https://player.bilibili.com/player.html?aid=733379562&bvid=BV1BD4y1Y7By&cid=913927393&page=1&high_quality=1" scrolling="no" border="0" frameborder="no" framespacing="0" allowfullscreen="true" width="100%" height="500"></iframe>!!
Here is how I forge the code:
- I requested the video from https://www.bilibili.com/video/BV1DV4y1A7uf/, its - bvidis- BV1DV4y1A7uf.
 
- Next, requested bilibili API for - cid: https://api.bilibili.com/x/player/pagelist?bvid=BV1DV4y1A7uf, it response:
 - {
 "code": 0,
 "message": "0",
 "ttl": 1,
 "data": [
 {
 "cid": 913960313,
 "page": 1,
 "from": "vupload",
 "part": "[spine-unity] 通过示例场景开始使用spine-unity运行时",
 ......
 }
 ]
 }
 
- so I get - cid = 913960313
 
- Then request https://api.bilibili.com/x/web-interface/view?cid=913960313&bvid=BV1DV4y1A7uf with - cid=913960313and- bvid=BV1DV4y1A7uf, got response with- aid:
 - {
 "code": 0,
 "message": "0",
 "ttl": 1,
 "data": {
 "bvid": "BV1DV4y1A7uf",
 "aid": 860908820,
 "videos": 1,
 "tid": 209,
 "tname": "职业职场",
 ......
 "need_jump_bv": false,
 "disable_show_up_info": false
 }
 }
 
- it said - aid=860908820
 
- In the end, put those 3 IDs together: - https://player.bilibili.com/player.html?aid=733379562&bvid=BV1BD4y1Y7By&cid=913927393, and got the iframe video play code
 
Hope my wild way work.
PS: this post mentioned the mobile bilibili player is more clean than www version, just replace player.bilibili.com/player.html to www.bilibili.com/blackboard/html5mobileplayer.html.