---
title: "YouTube playback test over a SIM"
sidebarTitle: "Youtube"
description: Stream a video over the cellular connection and measure playback quality.
lastUpdated: "2026-09-23"
---

> **For AI agents:** the complete documentation index is at [llms.txt](/llms.txt). Append `.md` to any page URL for its markdown version.

Stream a video over the SIM's data connection and measure the experience: time to first frame, buffering events, dropped pictures, achieved quality. The closest measurement to what a subscriber feels when watching video on the network.

## Parameters

| Parameter | Required | Description |
| ----------- | ---------- | ------------- |
| Url | Yes | The video URL to stream. |
| Quality | No | Requested video quality. Default: `144p`. |
| Duration to play | No | How long to stream, in seconds. Default: 10. |

Plus the shared [connection settings](/tests/actions/cellular/overview#connection-settings).

## Results and metrics

In the action report (`result`):

| Field | Description |
|-------|-------------|
| `first_buffering_time` | Time before playback starts. |
| `additional_buffering_time`, `additional_buffering_count` | Re-buffering during playback: total time and number of stalls. |
| `played_time` | Seconds actually played. |
| `displayed_pictures`, `lost_pictures` | Frames displayed versus dropped. |
| `played_audio_buffers`, `lost_audio_buffers` | Audio continuity. |
| `streamed_quality`, `best_available_quality`, `codec` | The quality obtained versus available, and the codec. |
| `total_bytes`, `read_bytes` | Data volume transferred. |

In Analytics, each run feeds the video measurement with the buffering times and counts, `lost_pictures_percent`, `buffering_percent`, played time, and volumes, tagged by status, streamed quality, APN, antenna, DNS server, and access technology.

## What's next?

<Columns cols={2}>
  <Card title="Ookla Speedtest" icon="gauge-high" href="/tests/actions/cellular/speedtest">

    Raw bandwidth, to correlate with video quality

</Card>
  <Card title="Download File" icon="cloud-arrow-down" href="/tests/actions/cellular/download-file">

    Plain throughput against your own servers

</Card>
</Columns>