Проблема в том, что вы используете json_decode($val, assoc: true)
Из документации php:
Когда TRUE, возвращаемые объекты будут преобразованы в ассоциативные массивы.
Так что просто не используйте true, и это должно относиться к вещам так, как вы хотите.
<?php
$json = '{
"kind": "youtube#videoListResponse",
"etag": "XI7nbFXulYBIpL0ayR_gDh3eu1k/wo842EqE4etxOSsLdlZIaoKM8M0",
"pageInfo": {
"totalResults": 1,
"resultsPerPage": 1
},
"items": [
{
"kind": "youtube#video",
"etag": "XI7nbFXulYBIpL0ayR_gDh3eu1k/HNnm6NCNPTGVCQmzWqpMBzSi9S8",
"id": "Mpxr7Rc0ycQ",
"snippet": {
"publishedAt": "2018-07-18T11:29:51.000Z",
"channelId": "UC8ezvxw6dD3dF5Xu9Aw7icA",
"title": "5 Weird Things Caught on Security Cameras & CCTV #2",
"description": "description",
"thumbnails": {
"default": {
"url": "https://i.ytimg.com/vi/Mpxr7Rc0ycQ/default.jpg",
"width": 120,
"height": 90
},
"medium": {
"url": "https://i.ytimg.com/vi/Mpxr7Rc0ycQ/mqdefault.jpg",
"width": 320,
"height": 180
},
"high": {
"url": "https://i.ytimg.com/vi/Mpxr7Rc0ycQ/hqdefault.jpg",
"width": 480,
"height": 360
},
"standard": {
"url": "https://i.ytimg.com/vi/Mpxr7Rc0ycQ/sddefault.jpg",
"width": 640,
"height": 480
}
}
}
}
]
}';
$val = json_decode($json);
print_r($val);
Преобразует в:
stdClass Object
(
[kind] => youtube#videoListResponse
[etag] => XI7nbFXulYBIpL0ayR_gDh3eu1k/wo842EqE4etxOSsLdlZIaoKM8M0
[pageInfo] => stdClass Object
(
[totalResults] => 1
[resultsPerPage] => 1
)
[items] => Array
(
[0] => stdClass Object
(
[kind] => youtube#video
[etag] => XI7nbFXulYBIpL0ayR_gDh3eu1k/HNnm6NCNPTGVCQmzWqpMBzSi9S8
[id] => Mpxr7Rc0ycQ
[snippet] => stdClass Object
(
[publishedAt] => 2018-07-18T11:29:51.000Z
[channelId] => UC8ezvxw6dD3dF5Xu9Aw7icA
[title] => 5 Weird Things Caught on Security Cameras & CCTV #2
[description] => description
[thumbnails] => stdClass Object
(
[default] => stdClass Object
(
[url] => https://i.ytimg.com/vi/Mpxr7Rc0ycQ/default.jpg
[width] => 120
[height] => 90
)
[medium] => stdClass Object
(
[url] => https://i.ytimg.com/vi/Mpxr7Rc0ycQ/mqdefault.jpg
[width] => 320
[height] => 180
)
[high] => stdClass Object
(
[url] => https://i.ytimg.com/vi/Mpxr7Rc0ycQ/hqdefault.jpg
[width] => 480
[height] => 360
)
[standard] => stdClass Object
(
[url] => https://i.ytimg.com/vi/Mpxr7Rc0ycQ/sddefault.jpg
[width] => 640
[height] => 480
)
)
)
)
)
)
stdClass
является внутренним эквивлантом PHP универсального object
.